Engineering › Biomedical Engineering

Advanced Sensor and Energy Harvesting Materials

Works Count: 92160

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Description

This cluster of papers focuses on the development of wearable nanogenerator technology, including flexible and stretchable sensors, triboelectric technology, energy harvesting, self-powered systems, electronic skin, and health monitoring. The research covers a wide range of materials and devices for integrating electronics into wearable and flexible formats for various applications.

Keywords

Wearable; Nanogenerators; Flexible Electronics; Stretchable Sensors; Triboelectric Technology; Energy Harvesting; Self-Powered Systems; Electronic Skin; Health Monitoring; Conductive Materials

Progress in triboelectric nanogenerators as a new energy technology and self-powered sensors

2015-01-01

Zhong Lin Wang , Jun Chen , Long Lin

A review on the principles, novel applications and perspectives of triboelectric nanogenerators as power sources and as self-powered sensors. A review on the principles, novel applications and perspectives of triboelectric nanogenerators as power sources and as self-powered sensors.

Stretchable active-matrix organic light-emitting diode display using printable elastic conductors

2009-05-10

Tsuyoshi Sekitani , Hiroyoshi Nakajima , Hiroki Maeda +4 more

Skin-like pressure and strain sensors based on transparent elastic films of carbon nanotubes

2011-10-23

Darren J. Lipomi , Michael Vosgueritchian , Benjamin C. K. Tee +4 more

Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays

2006-04-13

Zhong Lin Wang , Jinhui Song

We have converted nanoscale mechanical energy into electrical energy by means of piezoelectric zinc oxide nanowire (NW) arrays. The aligned NWs are deflected with a conductive atomic force microscope tip … We have converted nanoscale mechanical energy into electrical energy by means of piezoelectric zinc oxide nanowire (NW) arrays. The aligned NWs are deflected with a conductive atomic force microscope tip in contact mode. The coupling of piezoelectric and semiconducting properties in zinc oxide creates a strain field and charge separation across the NW as a result of its bending. The rectifying characteristic of the Schottky barrier formed between the metal tip and the NW leads to electrical current generation. The efficiency of the NW-based piezoelectric power generator is estimated to be 17 to 30%. This approach has the potential of converting mechanical, vibrational, and/or hydraulic energy into electricity for powering nanodevices.

Piezoelectricity of single-atomic-layer MoS2 for energy conversion and piezotronics

2014-10-01

Wenzhuo Wu , Lei Wang , Yilei Li +7 more

25th Anniversary Article: The Evolution of Electronic Skin (E‐Skin): A Brief History, Design Considerations, and Recent Progress

2013-10-22

Mallory L. Hammock , Alex Chortos , Benjamin C. K. Tee +2 more

Human skin is a remarkable organ. It consists of an integrated, stretchable network of sensors that relay information about tactile and thermal stimuli to the brain, allowing us to maneuver … Human skin is a remarkable organ. It consists of an integrated, stretchable network of sensors that relay information about tactile and thermal stimuli to the brain, allowing us to maneuver within our environment safely and effectively. Interest in large-area networks of electronic devices inspired by human skin is motivated by the promise of creating autonomous intelligent robots and biomimetic prosthetics, among other applications. The development of electronic networks comprised of flexible, stretchable, and robust devices that are compatible with large-area implementation and integrated with multiple functionalities is a testament to the progress in developing an electronic skin (e-skin) akin to human skin. E-skins are already capable of providing augmented performance over their organic counterpart, both in superior spatial resolution and thermal sensitivity. They could be further improved through the incorporation of additional functionalities (e.g., chemical and biological sensing) and desired properties (e.g., biodegradability and self-powering). Continued rapid progress in this area is promising for the development of a fully integrated e-skin in the near future.

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A stretchable carbon nanotube strain sensor for human-motion detection

2011-03-27

Takeo Yamada , Yuhei Hayamizu , Yuki Yamamoto +4 more

Highly Stretchable and Sensitive Strain Sensor Based on Silver Nanowire–Elastomer Nanocomposite

2014-04-21

Morteza Amjadi , Aekachan Pichitpajongkit , Sang‐Jun Lee +2 more

The demand for flexible and wearable electronic devices is increasing due to their facile interaction with human body. Flexible, stretchable and wearable sensors can be easily mounted on clothing or … The demand for flexible and wearable electronic devices is increasing due to their facile interaction with human body. Flexible, stretchable and wearable sensors can be easily mounted on clothing or directly attached onto the body. Especially, highly stretchable and sensitive strain sensors are needed for the human motion detection. Here, we report highly flexible, stretchable and sensitive strain sensors based on the nanocomposite of silver nanowire (AgNW) network and PDMS elastomer in the form of the sandwich structure (i.e., AgNW thin film embedded between two layers of PDMS). The AgNW network-elastomer nanocomposite based strain sensors show strong piezoresistivity with tunable gauge factors in the ranges of 2 to 14 and a high stretchability up to 70%. We demonstrate the applicability of our high performance strain sensors by fabricating a glove integrated with five strain sensors for the motion detection of fingers and control of an avatar in the virtual environment.

Direct-Current Nanogenerator Driven by Ultrasonic Waves

2007-04-05

Xudong Wang , Jinhui Song , Liu Jin +1 more

We have developed a nanowire nanogenerator that is driven by an ultrasonic wave to produce continuous direct-current output. The nanogenerator was fabricated with vertically aligned zinc oxide nanowire arrays that … We have developed a nanowire nanogenerator that is driven by an ultrasonic wave to produce continuous direct-current output. The nanogenerator was fabricated with vertically aligned zinc oxide nanowire arrays that were placed beneath a zigzag metal electrode with a small gap. The wave drives the electrode up and down to bend and/or vibrate the nanowires. A piezoelectric-semiconducting coupling process converts mechanical energy into electricity. The zigzag electrode acts as an array of parallel integrated metal tips that simultaneously and continuously create, collect, and output electricity from all of the nanowires. The approach presents an adaptable, mobile, and cost-effective technology for harvesting energy from the environment, and it offers a potential solution for powering nanodevices and nanosystems.

A wearable and highly sensitive pressure sensor with ultrathin gold nanowires

2014-02-04

Shu Gong , Willem Schwalb , Yongwei Wang +5 more

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Emerging Transparent Electrodes Based on Thin Films of Carbon Nanotubes, Graphene, and Metallic Nanostructures

2011-02-15

David S. Hecht , Liangbing Hu , Glen Irvin

Abstract Transparent electrodes are a necessary component in many modern devices such as touch screens, LCDs, OLEDs, and solar cells, all of which are growing in demand. Traditionally, this role … Abstract Transparent electrodes are a necessary component in many modern devices such as touch screens, LCDs, OLEDs, and solar cells, all of which are growing in demand. Traditionally, this role has been well served by doped metal oxides, the most common of which is indium tin oxide, or ITO. Recently, advances in nano‐materials research have opened the door for other transparent conductive materials, each with unique properties. These include CNTs, graphene, metal nanowires, and printable metal grids. This review will explore the materials properties of transparent conductors, covering traditional metal oxides and conductive polymers initially, but with a focus on current developments in nano‐material coatings. Electronic, optical, and mechanical properties of each material will be discussed, as well as suitability for various applications.

A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications

2004-06-28

Takao Someya , Tsuyoshi Sekitani , Shingo Iba +3 more

It is now widely accepted that skin sensitivity will be very important for future robots used by humans in daily life for housekeeping and entertainment purposes. Despite this fact, relatively … It is now widely accepted that skin sensitivity will be very important for future robots used by humans in daily life for housekeeping and entertainment purposes. Despite this fact, relatively little progress has been made in the field of pressure recognition compared to the areas of sight and voice recognition, mainly because good artificial “electronic skin” with a large area and mechanical flexibility is not yet available. The fabrication of a sensitive skin consisting of thousands of pressure sensors would require a flexible switching matrix that cannot be realized with present silicon-based electronics. Organic field-effect transistors can substitute for such conventional electronics because organic circuits are inherently flexible and potentially ultralow in cost even for a large area. Thus, integration of organic transistors and rubber pressure sensors, both of which can be produced by low-cost processing technology such as large-area printing technology, will provide an ideal solution to realize a practical artificial skin, whose feasibility has been demonstrated in this paper. Pressure images have been taken by flexible active matrix drivers with organic transistors whose mobility reaches as high as 1.4 cm 2 /V·s. The device is electrically functional even when it is wrapped around a cylindrical bar with a 2-mm radius.

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Wearable Electronics and Smart Textiles: A Critical Review

2014-07-07

Matteo Stoppa , Alessandro Chiolerio

Electronic Textiles (e-textiles) are fabrics that feature electronics and interconnections woven into them, presenting physical flexibility and typical size that cannot be achieved with other existing electronic manufacturing techniques. Components … Electronic Textiles (e-textiles) are fabrics that feature electronics and interconnections woven into them, presenting physical flexibility and typical size that cannot be achieved with other existing electronic manufacturing techniques. Components and interconnections are intrinsic to the fabric and thus are less visible and not susceptible of becoming tangled or snagged by surrounding objects. E-textiles can also more easily adapt to fast changes in the computational and sensing requirements of any specific application, this one representing a useful feature for power management and context awareness. The vision behind wearable computing foresees future electronic systems to be an integral part of our everyday outfits. Such electronic devices have to meet special requirements concerning wearability. Wearable systems will be characterized by their ability to automatically recognize the activity and the behavioral status of their own user as well as of the situation around her/him, and to use this information to adjust the systems' configuration and functionality. This review focuses on recent advances in the field of Smart Textiles and pays particular attention to the materials and their manufacturing process. Each technique shows advantages and disadvantages and our aim is to highlight a possible trade-off between flexibility, ergonomics, low power consumption, integration and eventually autonomy.

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Silver Nanowire Networks as Flexible, Transparent, Conducting Films: Extremely High DC to Optical Conductivity Ratios

2009-06-24

Sukanta De , Thomas M. Higgins , Philip E. Lyons +5 more

We have used aqueous dispersions of silver nanowires to prepare thin, flexible, transparent, conducting films. The nanowires are of length and diameter close to 6.5 μm and 85 nm, respectively. … We have used aqueous dispersions of silver nanowires to prepare thin, flexible, transparent, conducting films. The nanowires are of length and diameter close to 6.5 μm and 85 nm, respectively. At low thickness, the films consist of networks but appear to become bulk-like for mean film thicknesses above ∼160 nm. These films can be very transparent with optical transmittance reaching as high as 92% for low thickness. The transmittance (550 nm) decreases with increasing thickness, consistent with an optical conductivity of 6472 S/m. The films are also very uniform; the transmittance varies spatially by typically <2%. The sheet resistance decreases with increasing thickness, falling below 1 Ω/◻ for thicknesses above 300 nm. The DC conductivity increases from 2 × 10(5) S/m for very thin films before saturating at 5 × 10(6) S/m for thicker films. Similarly, the ratio of DC to optical conductivity increases with increasing thickness from 25 for the thinnest films, saturating at ∼500 for thicknesses above ∼160 nm. We believe this is the highest conductivity ratio ever observed for nanostructured films and is matched only by doped metal oxide films. These nanowire films are electromechanically very robust, with all but the thinnest films showing no change in sheet resistance when flexed over >1000 cycles. Such results make these films ideal as replacements for indium tin oxide as transparent electrodes. We have prepared films with optical transmittance and sheet resistance of 85% and 13 Ω/◻, respectively. This is very close to that displayed by commercially available indium tin oxide.

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Electroactive phases of poly(vinylidene fluoride): Determination, processing and applications

2013-07-19

P. Martins , Ana Catarina Lopes , S. Lanceros‐Méndez

Theoretical study of contact-mode triboelectric nanogenerators as an effective power source

2013-01-01

Simiao Niu , Sihong Wang , Long Lin +4 more

A theoretical model for contact-mode TENGs was constructed in this paper. Based on the theoretical model, its real-time output characteristics and the relationship between the optimum resistance and TENG parameters … A theoretical model for contact-mode TENGs was constructed in this paper. Based on the theoretical model, its real-time output characteristics and the relationship between the optimum resistance and TENG parameters were derived. The theory presented here is the first in-depth interpretation of the contact-mode TENG, which can serve as important guidance for rational design of the TENG structure in specific applications.

Triboelectric Nanogenerators as New Energy Technology for Self-Powered Systems and as Active Mechanical and Chemical Sensors

2013-09-30

Zhong Lin Wang

Triboelectrification is an effect that is known to each and every one probably since ancient Greek time, but it is usually taken as a negative effect and is avoided in … Triboelectrification is an effect that is known to each and every one probably since ancient Greek time, but it is usually taken as a negative effect and is avoided in many technologies. We have recently invented a triboelectric nanogenerator (TENG) that is used to convert mechanical energy into electricity by a conjunction of triboelectrification and electrostatic induction. As for this power generation unit, in the inner circuit, a potential is created by the triboelectric effect due to the charge transfer between two thin organic/inorganic films that exhibit opposite tribo-polarity; in the outer circuit, electrons are driven to flow between two electrodes attached on the back sides of the films in order to balance the potential. Since the most useful materials for TENG are organic, it is also named organic nanogenerator, which is the first using organic materials for harvesting mechanical energy. In this paper, we review the fundamentals of the TENG in the three basic operation modes: vertical contact-separation mode, in-plane sliding mode, and single-electrode mode. Ever since the first report of the TENG in January 2012, the output power density of TENG has been improved 5 orders of magnitude within 12 months. The area power density reaches 313 W/m(2), volume density reaches 490 kW/m(3), and a conversion efficiency of ∼60% has been demonstrated. The TENG can be applied to harvest all kinds of mechanical energy that is available but wasted in our daily life, such as human motion, walking, vibration, mechanical triggering, rotating tire, wind, flowing water, and more. Alternatively, TENG can also be used as a self-powered sensor for actively detecting the static and dynamic processes arising from mechanical agitation using the voltage and current output signals of the TENG, respectively, with potential applications for touch pad and smart skin technologies. To enhance the performance of the TENG, besides the vast choices of materials in the triboelectric series, from polymer to metal and to fabric, the morphologies of their surfaces can be modified by physical techniques with the creation of pyramid-, square-, or hemisphere-based micro- or nanopatterns, which are effective for enhancing the contact area and possibly the triboelectrification. The surfaces of the materials can be functionalized chemically using various molecules, nanotubes, nanowires, or nanoparticles, in order to enhance the triboelectric effect. The contact materials can be composites, such as embedding nanoparticles in a polymer matrix, which may change not only the surface electrification but also the permittivity of the materials so that they can be effective for electrostatic induction. Therefore, there are numerous ways to enhance the performance of the TENG from the materials point of view. This gives an excellent opportunity for chemists and materials scientists to do extensive study both in the basic science and in practical applications. We anticipate that a better enhancement of the output power density will be achieved in the next few years. The TENG is possible not only for self-powered portable electronics but also as a new energy technology with potential to contribute to the world energy in the near future.

Fiber‐Based Wearable Electronics: A Review of Materials, Fabrication, Devices, and Applications

2014-06-18

Wei Zeng , Lin Shu , Qiao Li +3 more

Fiber‐based structures are highly desirable for wearable electronics that are expected to be light‐weight, long‐lasting, flexible, and conformable. Many fibrous structures have been manufactured by well‐established lost‐effective textile processing technologies, … Fiber‐based structures are highly desirable for wearable electronics that are expected to be light‐weight, long‐lasting, flexible, and conformable. Many fibrous structures have been manufactured by well‐established lost‐effective textile processing technologies, normally at ambient conditions. The advancement of nanotechnology has made it feasible to build electronic devices directly on the surface or inside of single fibers, which have typical thickness of several to tens microns. However, imparting electronic functions to porous, highly deformable and three‐dimensional fiber assemblies and maintaining them during wear represent great challenges from both views of fundamental understanding and practical implementation. This article attempts to critically review the current state‐of‐arts with respect to materials, fabrication techniques, and structural design of devices as well as applications of the fiber‐based wearable electronic products. In addition, this review elaborates the performance requirements of the fiber‐based wearable electronic products, especially regarding the correlation among materials, fiber/textile structures and electronic as well as mechanical functionalities of fiber‐based electronic devices. Finally, discussions will be presented regarding to limitations of current materials, fabrication techniques, devices concerning manufacturability and performance as well as scientific understanding that must be improved prior to their wide adoption.

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Stretchable, Transparent, Ionic Conductors

2013-08-29

Christoph Keplinger , Jeong‐Yun Sun , Choon Chiang Foo +3 more

Existing stretchable, transparent conductors are mostly electronic conductors. They limit the performance of interconnects, sensors, and actuators as components of stretchable electronics and soft machines. We describe a class of … Existing stretchable, transparent conductors are mostly electronic conductors. They limit the performance of interconnects, sensors, and actuators as components of stretchable electronics and soft machines. We describe a class of devices enabled by ionic conductors that are highly stretchable, fully transparent to light of all colors, and capable of operation at frequencies beyond 10 kilohertz and voltages above 10 kilovolts. We demonstrate a transparent actuator that can generate large strains and a transparent loudspeaker that produces sound over the entire audible range. The electromechanical transduction is achieved without electrochemical reaction. The ionic conductors have higher resistivity than many electronic conductors; however, when large stretchability and high transmittance are required, the ionic conductors have lower sheet resistance than all existing electronic conductors.

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The Piezoelectricity of Poly (vinylidene Fluoride)

1969-07-01

Heiji Kawai

Embedded 3D Printing of Strain Sensors within Highly Stretchable Elastomers

2014-06-16

Joseph T. Muth , Daniel M. Vogt , Ryan L. Truby +4 more

A new method, embedded-3D printing (e-3DP), is reported for fabricating strain sensors within highly conformal and extensible elastomeric matrices. e-3DP allows soft sensors to be created in nearly arbitrary planar … A new method, embedded-3D printing (e-3DP), is reported for fabricating strain sensors within highly conformal and extensible elastomeric matrices. e-3DP allows soft sensors to be created in nearly arbitrary planar and 3D motifs in a highly programmable and seamless manner. Several embodiments are demonstrated and sensor performance is characterized. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

An ultra-lightweight design for imperceptible plastic electronics

2013-07-01

Martin Kaltenbrunner , Tsuyoshi Sekitani , Jonathan T. Reeder +7 more

Flexible polymer transistors with high pressure sensitivity for application in electronic skin and health monitoring

2013-05-14

Gregor Schwartz , Benjamin C. K. Tee , Jianguo Mei +4 more

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A flexible and highly sensitive strain-gauge sensor using reversible interlocking of nanofibres

2012-07-27

Changhyun Pang , Gil-Yong Lee , Tae‐il Kim +4 more

Triboelectric nanogenerators as new energy technology and self-powered sensors – Principles, problems and perspectives

2014-01-01

Zhong Lin Wang

Triboelectrification is one of the most common effects in our daily life, but it is usually taken as a negative effect with very limited positive applications. Here, we invented a … Triboelectrification is one of the most common effects in our daily life, but it is usually taken as a negative effect with very limited positive applications. Here, we invented a triboelectric nanogenerator (TENG) based on organic materials that is used to convert mechanical energy into electricity. The TENG is based on the conjunction of triboelectrification and electrostatic induction, and it utilizes the most common materials available in our daily life, such as papers, fabrics, PTFE, PDMS, Al, PVC<italic>etc.</italic>In this short review, we first introduce the four most fundamental modes of TENG, based on which a range of applications have been demonstrated. The area power density reaches 1200 W m−2, volume density reaches 490 kW m−3, and an energy conversion efficiency of ∼50–85% has been demonstrated. The TENG can be applied to harvest all kinds of mechanical energy that is available in our daily life, such as human motion, walking, vibration, mechanical triggering, rotation energy, wind, a moving automobile, flowing water, rain drops, tide and ocean waves. Therefore, it is a new paradigm for energy harvesting. Furthermore, TENG can be a sensor that directly converts a mechanical triggering into a self-generated electric signal for detection of motion, vibration, mechanical stimuli, physical touching, and biological movement. After a summary of TENG for micro-scale energy harvesting, mega-scale energy harvesting, and self-powered systems, we will present a set of questions that need to be discussed and explored for applications of the TENG. Lastly, since the energy conversion efficiencies for each mode can be different although the materials are the same, depending on the triggering conditions and design geometry. But one common factor that determines the performance of all the TENGs is the charge density on the two surfaces, the saturation value of which may independent of the triggering configurations of the TENG. Therefore, the triboelectric charge density or the relative charge density in reference to a standard material (such as polytetrafluoroethylene (PTFE)) can be taken as a measuring matrix for characterizing the performance of the material for the TENG.

Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers

2010-09-12

Stefan C. B. Mannsfeld , Benjamin C. K. Tee , Randall M. Stoltenberg +6 more

Deterministic transfer of two-dimensional materials by all-dry viscoelastic stamping

2014-04-04

Andrés Castellanos-Gómez , Michele Buscema , Rianda Molenaar +4 more

The deterministic transfer of two-dimensional crystals constitutes a crucial step towards the fabrication of heterostructures based on the artificial stacking of two-dimensional materials. Moreover, controlling the positioning of two-dimensional crystals … The deterministic transfer of two-dimensional crystals constitutes a crucial step towards the fabrication of heterostructures based on the artificial stacking of two-dimensional materials. Moreover, controlling the positioning of two-dimensional crystals facilitates their integration in complex devices, which enables the exploration of novel applications and the discovery of new phenomena in these materials. To date, deterministic transfer methods rely on the use of sacrificial polymer layers and wet chemistry to some extent. Here, we develop an all-dry transfer method that relies on viscoelastic stamps and does not employ any wet chemistry step. This is found to be very advantageous to freely suspend these materials as there are no capillary forces involved in the process. Moreover, the whole fabrication process is quick, efficient, clean and it can be performed with high yield.

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Self-powered nanowire devices

2010-03-28

Sheng Xu , Yong Qin , Chen Xu +3 more

Materials and Mechanics for Stretchable Electronics

2010-03-25

John A. Rogers , Takao Someya , Yonggang Huang

Recent advances in mechanics and materials provide routes to integrated circuits that can offer the electrical properties of conventional, rigid wafer-based technologies but with the ability to be stretched, compressed, … Recent advances in mechanics and materials provide routes to integrated circuits that can offer the electrical properties of conventional, rigid wafer-based technologies but with the ability to be stretched, compressed, twisted, bent, and deformed into arbitrary shapes. Inorganic and organic electronic materials in microstructured and nanostructured forms, intimately integrated with elastomeric substrates, offer particularly attractive characteristics, with realistic pathways to sophisticated embodiments. Here, we review these strategies and describe applications of them in systems ranging from electronic eyeball cameras to deformable light-emitting displays. We conclude with some perspectives on routes to commercialization, new device opportunities, and remaining challenges for research.

Transparent Triboelectric Nanogenerators and Self-Powered Pressure Sensors Based on Micropatterned Plastic Films

2012-05-11

Feng Ru Fan , Long Lin , Guang Zhu +3 more

Transparent, flexible and high efficient power sources are important components of organic electronic and optoelectronic devices. In this work, based on the principle of the previously demonstrated triboelectric generator, we … Transparent, flexible and high efficient power sources are important components of organic electronic and optoelectronic devices. In this work, based on the principle of the previously demonstrated triboelectric generator, we demonstrate a new high-output, flexible and transparent nanogenerator by using transparent polymer materials. We have fabricated three types of regular and uniform polymer patterned arrays (line, cube, and pyramid) to improve the efficiency of the nanogenerator. The power generation of the pyramid-featured device far surpassed that exhibited by the unstructured films and gave an output voltage of up to 18 V at a current density of ∼0.13 μA/cm(2). Furthermore, the as-prepared nanogenerator can be applied as a self-powered pressure sensor for sensing a water droplet (8 mg, ∼3.6 Pa in contact pressure) and a falling feather (20 mg, ∼0.4 Pa in contact pressure) with a low-end detection limit of ∼13 mPa.

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Stretchable and Foldable Silicon Integrated Circuits

2008-03-28

Dae‐Hyeong Kim , Jong‐Hyun Ahn , Won Mook Choi +7 more

We have developed a simple approach to high-performance, stretchable, and foldable integrated circuits. The systems integrate inorganic electronic materials, including aligned arrays of nanoribbons of single crystalline silicon, with ultrathin … We have developed a simple approach to high-performance, stretchable, and foldable integrated circuits. The systems integrate inorganic electronic materials, including aligned arrays of nanoribbons of single crystalline silicon, with ultrathin plastic and elastomeric substrates. The designs combine multilayer neutral mechanical plane layouts and “wavy” structural configurations in silicon complementary logic gates, ring oscillators, and differential amplifiers. We performed three-dimensional analytical and computational modeling of the mechanics and the electronic behaviors of these integrated circuits. Collectively, the results represent routes to devices, such as personal health monitors and other biomedical devices, that require extreme mechanical deformations during installation/use and electronic properties approaching those of conventional systems built on brittle semiconductor wafers.

Flexible triboelectric generator

2012-01-20

Feng Ru Fan , Zhong‐Qun Tian , Zhong Lin Wang

Tactile Sensing—From Humans to Humanoids

2009-11-30

Ravinder Dahiya , Giorgio Metta , Maurizio Valle +1 more

Starting from human ¿sense of touch,¿ this paper reviews the state of tactile sensing in robotics. The physiology, coding, and transferring tactile data and perceptual importance of the ¿sense of … Starting from human ¿sense of touch,¿ this paper reviews the state of tactile sensing in robotics. The physiology, coding, and transferring tactile data and perceptual importance of the ¿sense of touch¿ in humans are discussed. Following this, a number of design hints derived for robotic tactile sensing are presented. Various technologies and transduction methods used to improve the touch sense capability of robots are presented. Tactile sensing, focused to fingertips and hands until past decade or so, has now been extended to whole body, even though many issues remain open. Trend and methods to develop tactile sensing arrays for various body sites are presented. Finally, various system issues that keep tactile sensing away from widespread utility are discussed.

Flexible Nanogenerators for Energy Harvesting and Self‐Powered Electronics

2016-01-07

Feng Ru Fan , Wei Tang , Zhong Lin Wang

Flexible nanogenerators that efficiently convert mechanical energy into electrical energy have been extensively studied because of their great potential for driving low‐power personal electronics and self‐powered sensors. Integration of flexibility … Flexible nanogenerators that efficiently convert mechanical energy into electrical energy have been extensively studied because of their great potential for driving low‐power personal electronics and self‐powered sensors. Integration of flexibility and stretchability to nanogenerator has important research significance that enables applications in flexible/stretchable electronics, organic optoelectronics, and wearable electronics. Progress in nanogenerators for mechanical energy harvesting is reviewed, mainly including two key technologies: flexible piezoelectric nanogenerators (PENGs) and flexible triboelectric nanogenerators (TENGs). By means of material classification, various approaches of PENGs based on ZnO nanowires, lead zirconate titanate (PZT), poly(vinylidene fluoride) (PVDF), 2D materials, and composite materials are introduced. For flexible TENG, its structural designs and factors determining its output performance are discussed, as well as its integration, fabrication and applications. The latest representative achievements regarding the hybrid nanogenerator are also summarized. Finally, some perspectives and challenges in this field are discussed.

Flexible and Stretchable Physical Sensor Integrated Platforms for Wearable Human‐Activity Monitoringand Personal Healthcare

2016-02-03

Tran Quang Trung , Nae‐Eung Lee

Flexible and stretchable physical sensors that can measure and quantify electrical signals generated by human activities are attracting a great deal of attention as they have unique characteristics, such as … Flexible and stretchable physical sensors that can measure and quantify electrical signals generated by human activities are attracting a great deal of attention as they have unique characteristics, such as ultrathinness, low modulus, light weight, high flexibility, and stretchability. These flexible and stretchable physical sensors conformally attached on the surface of organs or skin can provide a new opportunity for human-activity monitoring and personal healthcare. Consequently, in recent years there has been considerable research effort devoted to the development of flexible and stretchable physical sensors to fulfill the requirements of future technology, and much progress has been achieved. Here, the most recent developments of flexible and stretchable physical sensors are described, including temperature, pressure, and strain sensors, and flexible and stretchable sensor-integrated platforms. The latest successful examples of flexible and stretchable physical sensors for the detection of temperature, pressure, and strain, as well as their novel structures, technological innovations, and challenges, are reviewed first. In the next section, recent progress regarding sensor-integrated wearable platforms is overviewed in detail. Some of the latest achievements regarding self-powered sensor-integrated wearable platform technologies are also reviewed. Further research direction and challenges are also proposed to develop a fully sensor-integrated wearable platform for monitoring human activity and personal healthcare in the near future.

Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis

2016-01-26

Wei Gao , Sam Emaminejad , Hnin Yin Yin Nyein +7 more

Stretchable, Skin‐Mountable, and Wearable Strain Sensors and Their Potential Applications: A Review

2016-02-17

Morteza Amjadi , Ki‐Uk Kyung , Inkyu Park +1 more

There is a growing demand for flexible and soft electronic devices. In particular, stretchable, skin‐mountable, and wearable strain sensors are needed for several potential applications including personalized health‐monitoring, human motion … There is a growing demand for flexible and soft electronic devices. In particular, stretchable, skin‐mountable, and wearable strain sensors are needed for several potential applications including personalized health‐monitoring, human motion detection, human‐machine interfaces, soft robotics, and so forth. This Feature Article presents recent advancements in the development of flexible and stretchable strain sensors. The article shows that highly stretchable strain sensors are successfully being developed by new mechanisms such as disconnection between overlapped nanomaterials, crack propagation in thin films, and tunneling effect, different from traditional strain sensing mechanisms. Strain sensing performances of recently reported strain sensors are comprehensively studied and discussed, showing that appropriate choice of composite structures as well as suitable interaction between functional nanomaterials and polymers are essential for the high performance strain sensing. Next, simulation results of piezoresistivity of stretchable strain sensors by computational models are reported. Finally, potential applications of flexible strain sensors are described. This survey reveals that flexible, skin‐mountable, and wearable strain sensors have potential in diverse applications while several grand challenges have to be still overcome.

Pursuing prosthetic electronic skin

2016-07-04

Alex Chortos , Jia Liu , Zhenan Bao

The rise of plastic bioelectronics

2016-12-13

Takao Someya , Zhenan Bao , George G. Malliaras

On Maxwell's displacement current for energy and sensors: the origin of nanogenerators

2017-01-07

Zhong Lin Wang

Self-powered system is a system that can sustainably operate without an external power supply for sensing, detection, data processing and data transmission. Nanogenerators were first developed for self-powered systems based … Self-powered system is a system that can sustainably operate without an external power supply for sensing, detection, data processing and data transmission. Nanogenerators were first developed for self-powered systems based on piezoelectric effect and triboelectrification effect for converting tiny mechanical energy into electricity, which have applications in internet of things, environmental/infrastructural monitoring, medical science and security. In this paper, we present the fundamental theory of the nanogenerators starting from the Maxwell equations. In the Maxwell's displacement current, the first term ε0∂E∂t gives the birth of electromagnetic wave, which is the foundation of wireless communication, radar and later the information technology. Our study indicates that the second term ∂P∂t in the Maxwell's displacement current is directly related to the output electric current of the nanogenerator, meaning that our nanogenerators are the applications of Maxwell's displacement current in energy and sensors. By contrast, electromagnetic generators are built based on Lorentz force driven flow of free electrons in a conductor. This study presents the similarity and differences between pieozoelectric nanogenerator and triboelectric nanogenerator, as well as the classical electromagnetic generator, so that the impact and uniqueness of the nanogenerators can be clearly understood. We also present the three major applications of nanogenerators as micro/nano-power source, self-powered sensors and blue energy.

Stretchable and Soft Electronics using Liquid Metals

2017-04-18

Michael D. Dickey

The use of liquid metals based on gallium for soft and stretchable electronics is discussed. This emerging class of electronics is motivated, in part, by the new opportunities that arise … The use of liquid metals based on gallium for soft and stretchable electronics is discussed. This emerging class of electronics is motivated, in part, by the new opportunities that arise from devices that have mechanical properties similar to those encountered in the human experience, such as skin, tissue, textiles, and clothing. These types of electronics (e.g., wearable or implantable electronics, sensors for soft robotics, e-skin) must operate during deformation. Liquid metals are compelling materials for these applications because, in principle, they are infinitely deformable while retaining metallic conductivity. Liquid metals have been used for stretchable wires and interconnects, reconfigurable antennas, soft sensors, self-healing circuits, and conformal electrodes. In contrast to Hg, liquid metals based on gallium have low toxicity and essentially no vapor pressure and are therefore considered safe to handle. Whereas most liquids bead up to minimize surface energy, the presence of a surface oxide on these metals makes it possible to pattern them into useful shapes using a variety of techniques, including fluidic injection and 3D printing. In addition to forming excellent conductors, these metals can be used actively to form memory devices, sensors, and diodes that are completely built from soft materials. The properties of these materials, their applications within soft and stretchable electronics, and future opportunities and challenges are considered.

Lab-on-Skin: A Review of Flexible and Stretchable Electronics for Wearable Health Monitoring

2017-09-13

Yuhao Liu , Matt Pharr , Giovanni A. Salvatore

Skin is the largest organ of the human body, and it offers a diagnostic interface rich with vital biological signals from the inner organs, blood vessels, muscles, and dermis/epidermis. Soft, … Skin is the largest organ of the human body, and it offers a diagnostic interface rich with vital biological signals from the inner organs, blood vessels, muscles, and dermis/epidermis. Soft, flexible, and stretchable electronic devices provide a novel platform to interface with soft tissues for robotic feedback and control, regenerative medicine, and continuous health monitoring. Here, we introduce the term "lab-on-skin" to describe a set of electronic devices that have physical properties, such as thickness, thermal mass, elastic modulus, and water-vapor permeability, which resemble those of the skin. These devices can conformally laminate on the epidermis to mitigate motion artifacts and mismatches in mechanical properties created by conventional, rigid electronics while simultaneously providing accurate, non-invasive, long-term, and continuous health monitoring. Recent progress in the design and fabrication of soft sensors with more advanced capabilities and enhanced reliability suggest an impending translation of these devices from the research lab to clinical environments. Regarding these advances, the first part of this manuscript reviews materials, design strategies, and powering systems used in soft electronics. Next, the paper provides an overview of applications of these devices in cardiology, dermatology, electrophysiology, and sweat diagnostics, with an emphasis on how these systems may replace conventional clinical tools. The review concludes with an outlook on current challenges and opportunities for future research directions in wearable health monitoring.

Skin electronics from scalable fabrication of an intrinsically stretchable transistor array

2018-02-16

Sihong Wang , Jie Xu , Weichen Wang +7 more

Triboelectric Nanogenerator: A Foundation of the Energy for the New Era

2018-11-19

Changsheng Wu , Aurelia Chi Wang , Wenbo Ding +2 more

Abstract As the world is marching into the era of the internet of things (IoTs) and artificial intelligence, the most vital development for hardware is a multifunctional array of sensing … Abstract As the world is marching into the era of the internet of things (IoTs) and artificial intelligence, the most vital development for hardware is a multifunctional array of sensing systems, which forms the foundation of the fourth industrial revolution toward an intelligent world. Given the need for mobility of these multitudes of sensors, the success of the IoTs calls for distributed energy sources, which can be provided by solar, thermal, wind, and mechanical triggering/vibrations. The triboelectric nanogenerator (TENG) for mechanical energy harvesting developed by Z.L. Wang's group is one of the best choices for this energy for the new era, since triboelectrification is a universal and ubiquitous effect with an abundant choice of materials. The development of self‐powered active sensors enabled by TENGs is revolutionary compared to externally powered passive sensors, similar to the advance from wired to wireless communication. In this paper, the fundamental theory, experiments, and applications of TENGs are reviewed as a foundation of the energy for the new era with four major application fields: micro/nano power sources, self‐powered sensors, large‐scale blue energy, and direct high‐voltage power sources. A roadmap is proposed for the research and commercialization of TENG in the next 10 years.

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Wearable biosensors for healthcare monitoring

2019-02-25

Jayoung Kim , Alan S. Campbell , Berta Esteban‐Fernández de Ávila +1 more

Quantifying the triboelectric series

2019-03-29

Haiyang Zou , Ying Zhang , Litong Guo +7 more

Abstract Triboelectrification is a well-known phenomenon that commonly occurs in nature and in our lives at any time and any place. Although each and every material exhibits triboelectrification, its quantification … Abstract Triboelectrification is a well-known phenomenon that commonly occurs in nature and in our lives at any time and any place. Although each and every material exhibits triboelectrification, its quantification has not been standardized. A triboelectric series has been qualitatively ranked with regards to triboelectric polarization. Here, we introduce a universal standard method to quantify the triboelectric series for a wide range of polymers, establishing quantitative triboelectrification as a fundamental materials property. By measuring the tested materials with a liquid metal in an environment under well-defined conditions, the proposed method standardizes the experimental set up for uniformly quantifying the surface triboelectrification of general materials. The normalized triboelectric charge density is derived to reveal the intrinsic character of polymers for gaining or losing electrons. This quantitative triboelectric series may serve as a textbook standard for implementing the application of triboelectrification for energy harvesting and self-powered sensing.

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Hydrogel bioelectronics

2018-11-26

Hyunwoo Yuk , Baoyang Lu , Xuanhe Zhao

Hydrogels have emerged as a promising bioelectronic interfacing material. This review discusses the fundamentals and recent advances in hydrogel bioelectronics. Hydrogels have emerged as a promising bioelectronic interfacing material. This review discusses the fundamentals and recent advances in hydrogel bioelectronics.

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A Stretchable Form of Single-Crystal Silicon for High-Performance Electronics on Rubber Substrates

2005-12-16

Dahl‐Young Khang , Hanqing Jiang , Young Huang +1 more

We have produced a stretchable form of silicon that consists of submicrometer single-crystal elements structured into shapes with microscale, periodic, wavelike geometries. When supported by an elastomeric substrate, this "wavy" … We have produced a stretchable form of silicon that consists of submicrometer single-crystal elements structured into shapes with microscale, periodic, wavelike geometries. When supported by an elastomeric substrate, this "wavy" silicon can be reversibly stretched and compressed to large levels of strain without damaging the silicon. The amplitudes and periods of the waves change to accommodate these deformations, thereby avoiding substantial strains in the silicon itself. Dielectrics, patterns of dopants, electrodes, and other elements directly integrated with the silicon yield fully formed, high-performance "wavy" metal oxide semiconductor field-effect transistors, p-n diodes, and other devices for electronic circuits that can be stretched or compressed to similarly large levels of strain.

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Epidermal Electronics

2011-08-11

Dae‐Hyeong Kim , Nanshu Lu , Rui Ma +7 more

We report classes of electronic systems that achieve thicknesses, effective elastic moduli, bending stiffnesses, and areal mass densities matched to the epidermis. Unlike traditional wafer-based technologies, laminating such devices onto … We report classes of electronic systems that achieve thicknesses, effective elastic moduli, bending stiffnesses, and areal mass densities matched to the epidermis. Unlike traditional wafer-based technologies, laminating such devices onto the skin leads to conformal contact and adequate adhesion based on van der Waals interactions alone, in a manner that is mechanically invisible to the user. We describe systems incorporating electrophysiological, temperature, and strain sensors, as well as transistors, light-emitting diodes, photodetectors, radio frequency inductors, capacitors, oscillators, and rectifying diodes. Solar cells and wireless coils provide options for power supply. We used this type of technology to measure electrical activity produced by the heart, brain, and skeletal muscles and show that the resulting data contain sufficient information for an unusual type of computer game controller.

Ferroelectric Polymers

1983-06-10

Andrew J. Lovinger

Piezoelectricity and pyroelectricity, traditionally encountered in certain single crystals and ceramics, have now also been documented in a number of polymers. Recently, one such polymer-poly(vinylidene fluoride)-and some of its copolymers … Piezoelectricity and pyroelectricity, traditionally encountered in certain single crystals and ceramics, have now also been documented in a number of polymers. Recently, one such polymer-poly(vinylidene fluoride)-and some of its copolymers have been shown to be ferroelectric as well. The extraordinary molecular and supermolecular structural requirements for ferroelectric behavior in polymers are discussed in detail, with particular emphasis on poly(vinylidene fluoride). Piezoelectric, pyroelectric, and ferroelectric properties are also briefly reviewed, as are some promising applications of such polymers.

Flexible Field‐Effect Transistor Sensors for Next‐Generation Health Monitoring: Materials to Advanced Applications

2025-06-25

Yaxin Li , Huige Hu , Jian Shu +1 more | Small

Abstract Flexible field‐effect transistor (FET) sensors have emerged as a promising technology for human health monitoring, driven by breakthroughs in materials, device design, and fabrication processes. Their unique advantages, including … Abstract Flexible field‐effect transistor (FET) sensors have emerged as a promising technology for human health monitoring, driven by breakthroughs in materials, device design, and fabrication processes. Their unique advantages, including multi‐parametric detection, intrinsic signal amplification, low power consumption, and scalable production, position them at the forefront of wearable and implantable biosensing systems. This review outlines the structural design and operational principles of flexible FET sensors, systematically summarizing material innovations for critical components (substrates, dielectrics, semiconductor channels, and electrodes) and strategies to harmonize electrical performance with mechanical robustness. It analyzes evaluation methods and optimization strategies for enhancing mechanical stability under repetitive strain, a pivotal challenge for practical deployment. Additionally, it highlights cutting‐edge applications in physiological signal monitoring and biological fluid analysis, demonstrating their potential for real‐time diagnostics. Finally, the review discusses the current limitations of flexible FET sensors and provides an outlook on their future opportunities in personalized health management, intelligent diagnostic systems, and next‐generation medical technologies.

An Intrinsically Stretchable Skin‐Adhesive Actuator With Structurally Anisotropic Multiphase Microarchitectures

2025-06-25

Jihun Son , Gui Won Hwang , Jin‐Ho Choi +7 more | Advanced Materials

Abstract Skin‐attachable actuators require robust adhesion and high‐fidelity feedback to conform to the skin under extreme deformation, integrating seamlessly while minimizing damping effects for diverse practical applications. Current rigid haptic … Abstract Skin‐attachable actuators require robust adhesion and high‐fidelity feedback to conform to the skin under extreme deformation, integrating seamlessly while minimizing damping effects for diverse practical applications. Current rigid haptic interfaces and soft dielectric materials are limited to operating effectively within specific resonance frequencies, exhibiting a mechanical mismatch with human skin, which reduces their effectiveness on highly deformable body parts and decreases the accuracy of vibration feedback. Moreover, intrinsically stretchable dielectric materials face challenges caused by layer integration and significant damping from single anisotropic architectures. Here, an intrinsically stretchable skin‐adhesive actuator (ISSA) with a multiphase dielectric architecture is presented that combines an isotropic spring matrix and an anisotropic elastic damper matrix, achieving stable vibration performance beyond the resonance frequency. The intrinsically stretchable electrode with its hybrid 1D/0D percolated structure ensures adaptability and reliable performance under strains exceeding 500%, whereas the frog‐inspired adhesive enhances skin conformity and breathability, providing robust shear strength (≈28.4 kPa) under extreme deformation. Owing to a seamlessly integrated design and ultralow modulus (<24 kPa), the skin‐adhesive actuator closely conforms to the human skin, delivering high vibrational acceleration while ensuring biocompatibility and durability for transformative applications in soft robotics, human–machine interfaces, and haptic technologies.

Design and fabrication of resistive sensor using additive manufacturing techniques for robotic application

2025-06-25

Donya MostaghniYazdi , Muhammad Usman Khalid , Mattia Frascio +1 more | The International Journal of Advanced Manufacturing Technology

A Poly (Vinylidene Fluoride‐Trifluoroethylene)‐Based Triboelectric and Piezoelectric Coefficient Generator for Energy Harvesting

2025-06-25

Xu Yan , Weimin Xia , Shaobing Zhou +2 more | Polymer Composites

ABSTRACT Nano piezoelectric or triboelectric generator shows the characteristics of light weight, good flexibility, portable, wearable, and so forth, which can effectively supply power for miniaturized electronic products. Herein, an … ABSTRACT Nano piezoelectric or triboelectric generator shows the characteristics of light weight, good flexibility, portable, wearable, and so forth, which can effectively supply power for miniaturized electronic products. Herein, an integrated piezoelectric and triboelectric generator (PE‐TENG) is assembled using a flexible polymer‐based functional film, where poly (vinylidene fuoride‐trifuoroethylene) (P(VDF‐TrFE)) is used as the matrix and the controllable polystyrene (C‐PS) microspheres as the filler. This PE‐TENG is operated by the triboelectric and piezoelectric effects coefficient, where TENG is in vertical contact‐separation mode, combined with the PENG in the longitudinal d31 piezoelectric mode, and converting the mechanical energy into electrical energy effectively. Consequently, the triboelectric nanogenerator (TENG) fabricated using the C‐PS/P(VDF‐TrFE)‐based composite film with 9 wt% C‐PS exhibits an impressive open‐circuit voltage of approximately 956 V and a remarkable short‐circuit current of around 8.75 μA. These outstanding electrical characteristics render it a highly promising candidate for applications in self‐powered sensing and wearable devices, demonstrating its potential to meet the power demands of such innovative technological domains.

A reusable hydrogel biosensor array with electrically responsive hydrogel interfaces for noninvasive locating of perforating arteries

2025-06-25

Ganguang Yang , Yuqi Qiu , Bo Pang +7 more | Science Advances

Achieving accurate locating of perforating arteries (PAs) has great clinical value in various biomedical applications, such as free flap transfer. However, the anatomical variability of these arteries presents a major … Achieving accurate locating of perforating arteries (PAs) has great clinical value in various biomedical applications, such as free flap transfer. However, the anatomical variability of these arteries presents a major challenge in PA locating, and existing methods have various disadvantages, limiting their applications. Here, we propose a reusable and flexible hydrogel biosensor array for noninvasive, precise, and efficient PA locating. Particularly, we develop electrically responsive hydrogels to establish rapidly detachable device/hydrogel interfaces, endowing the reusability of the biosensor array. Meanwhile, the adhesion of hydrogel/skin interfaces is also enhanced to facilitate high-fidelity signal acquisition. By analyzing the photoplethysmography (PPG) infrared (IR) signals, the biosensor array can accurately and responsively locate PAs across different types of free flaps in clinical cases, outperforming existing techniques. This biosensor array represents a promising platform for PA locating. The strategy of hydrogel interface design paves the way for the development of reusable flexible electronics in biomedical applications to avoid cross-infection and reduce device costs.

Laser engraved graphene-based ink-modified flexible electrochemical l-lactate sensor

2025-06-25

G. M. Mehedi Hossain , J.G. Garza , Pritu Parna Sarkar +6 more | MRS Advances

Integrated Triboelectric Nanogenerator and Photovoltaic Systems Using InP/ZnSe Quantum Dots for Smart Security Applications

2025-06-25

Yudong Wang , Junhui He , Haixin Li +6 more | ACS Applied Materials & Interfaces

In this study, cadmium-free InP/ZnSe core-shell quantum dots (QDs) were synthesized using the hot-injection method, with the measured barrier height of the PN junction being approximately 0.441 eV. The core-shell … In this study, cadmium-free InP/ZnSe core-shell quantum dots (QDs) were synthesized using the hot-injection method, with the measured barrier height of the PN junction being approximately 0.441 eV. The core-shell structure significantly improved the photoluminescence quantum yield (PLQY) compared to that of bare InP QDs, with enhanced optical properties and stability due to effective lattice matching between InP and ZnSe, reducing interfacial defects. These QDs were integrated into a hybrid energy-harvesting device by combining a triboelectric nanogenerator (TENG) and a photovoltaic (PV) thin film. The TENG, based on a PMMA-QDs composite film, achieved a high output power density of 191.13 μW/cm2 under 3 Hz mechanical excitation, while the PV device exhibited a light-switching ratio as high as 73.5, demonstrating excellent photoresponsivity. Additionally, a smart security lock system was developed, utilizing the TENG's personal information recognition capability to authorize access based on a friction-generated electrical signal, with an integrated alarm system to detect unauthorized code acquisition via light-excited fluorescent substances. This dual-response energy system offers a promising approach for efficient and reliable energy harvesting with potential applications in sustainable electronics and self-powered IoT devices.

Ultra‐Low Hysteresis Under Large Deformation Enabled by Fast Chains Relaxation in Highly Competitive Dynamic Hydrogen Bond Networks

2025-06-25

Shuaijun Guo , Shilei Zhu , Yang Qiao +7 more | Advanced Science

Abstract High‐quality capture of diverse motion signals in flexible sensors requires soft sensing materials to perform signal conversion and transmission stably and without delay over extended periods. However, low hysteresis … Abstract High‐quality capture of diverse motion signals in flexible sensors requires soft sensing materials to perform signal conversion and transmission stably and without delay over extended periods. However, low hysteresis achieved through purely elastic mechanisms easily exhibits poor crack propagation resistance. By leveraging the significant gap between the strain rate during large‐strain service conditions and the crack propagation rate in the fracture process, this study presents a facile strategy for constructing a highly competitive dynamic hydrogen bonding system to produce near‐zero‐hysteresis and highly crack‐resistant D‐gels. Through tuning the relaxation dynamics of strong hydrogen bonding interactions with polymer segments by insert deep eutectic solvent (DES) components, the highly dynamic hydrogen bonds are rendered mechanically “invisible” during service condition—an essential factor in achieving a low‐hysteresis attribute (low hysteresis: <3%). Meanwhile, the relaxation time of those dynamic bonds is comparable to the inverse of crack propagation rate, effectively alleviating stress concentration at the crack tips, thereby enhancing the ultimate fracture strain (1500%) and crack propagation strain (550%) of the gels. This approach provides a general strategy for synthesizing gels that overcome the traditional trade‐off between high crack propagation resistance and high elasticity.

Healable Dielectric Elastomer Actuator With Premature Breakdown Warning Function for Information Transmission Encryption and Human‐Machine Interaction

2025-06-25

Yanze Liu , Shilin Luo , Jiawei Zhao +3 more | Advanced Science

Abstract Dielectric elastomer actuators (DEAs), regarded as artificial muscles, are used as actuators or sensors in artificial visual systems, haptic equipment, and human‐robot interaction. However, their inherent vulnerability related to … Abstract Dielectric elastomer actuators (DEAs), regarded as artificial muscles, are used as actuators or sensors in artificial visual systems, haptic equipment, and human‐robot interaction. However, their inherent vulnerability related to mechanical damage and electrical breakdown seriously limits their safe and long‐term service. Herein, a healable dielectric elastomer (PHT‐ZnS:Cu) is acquired for premature breakdown warning by synthesising a healable poly(dimethylsiloxane) based on reversible imine bonding and hydrogen bonding and subsequent incorporation of electroluminescent ZnS:Cu particles. Moreover, LiTFSI ionic liquids are introduced into the healable poly(dimethylsiloxane) to prepare a transparent healable compliant electrode (PHT‐IL) that does not obscure the light emission of PHT‐ZnS:Cu dielectric elastomer. Then, an integral healable DEA (ISDEA) with an excellent interfacial interaction is constructed by coating two sides of PHT‐ZnS:Cu with PHT‐IL. The optimized ISDEA displays an actuated strain of 17.0% at 15 kV mm −1 with a healing efficiency of 91.9%. The integrated ISDEAs are used as soft anti‐counterfeiting labels and soft intelligent keyboards for information transmission, encryption, and human‐machine interaction, showing prospective applications in the realm of data leakage prevention and personal privacy protection.

Nanoporous Capillary Gripper for Ultragentle Micro‐Object Manipulation

2025-06-25

Seong Jae Kim , Taehoon Kim , Hyun Jun Ryu +3 more | Advanced Science

Abstract Surfaces become “sticky” at the micro/nano length scale as the gravitational force is no longer effective. Ultragentle, high‐contrast switching of interfacial adhesion is the key to reliable small‐scale object … Abstract Surfaces become “sticky” at the micro/nano length scale as the gravitational force is no longer effective. Ultragentle, high‐contrast switching of interfacial adhesion is the key to reliable small‐scale object manipulation. Here, a novel approach is presented for surface adhesion control utilizing a liquid‐permeable nanoporous surface, which can switch from off‐state adhesion (< 0.002 kPa) to on‐state attraction (0.8 kPa) without preload. The surface of the gripper is composed of vertically aligned composite nanowires with an average diameter of 79 nm. When a liquid is injected into the nanoporous membrane, capillary adhesion occurs, allowing the object to be picked up. As the liquid evaporates, the object can be released by extremely sparse contact. The off‐state adhesion of a millimeter‐scale gripper is even lower than the gravitational force of thin polymer films (0.18 mN cm −2 ), enabling the solid‐contactless release of lightweight materials. We characterize and model the mechanism across length scales and provide pick‐and‐place demonstrations including LED chips, micro‐architected materials, and thin‐film electronics.

The Stimulus-Expansion-Model for representing arbitrary active behavior in smart materials

2025-06-25

Adrian Ehrenhofer , Thomas Wallmersperger | Acta Mechanica

Tribovoltaic Effect at Liquid–MoS2 Interfaces and Spectral Analysis of Interfacial Charge Transfer

2025-06-25

Yaxuan Xie , Qingzhang You , Wenjing Bo +5 more | Advanced Materials

Abstract Liquid–solid triboelectric nanogenerators (TENGs) offer a viable approach for harvesting water energy to power Internet of Things systems. Semiconductor‐based TENGs leveraging the tribovoltaic effect have recently emerged as a … Abstract Liquid–solid triboelectric nanogenerators (TENGs) offer a viable approach for harvesting water energy to power Internet of Things systems. Semiconductor‐based TENGs leveraging the tribovoltaic effect have recently emerged as a focus of research. In this paper, monolayer molybdenum disulfide (ML‐MoS 2 ) is introduced as a contacting material for fabricating direct current (DC) liquid–solid nanogenerators. At the internal liquid–solid interface, electron transfer is strongly evidenced by Raman and photoluminescence spectra. For the external characteristics, macroscopic DC outputs are assessed under various conditions, with a maximum current density of 11.1 mA m −2 . Correlating external output patterns with interfacial charge dynamics, a complete working mechanism of the liquid–solid tribovoltaic effect is better elucidated. This work advances innovative strategies for water energy harvesting, deepening fundamental insights into liquid–solid interactions and the tribovoltaic effect.

Biomaterial‐Based Fibrous Implantable Probes for Tissue‐Electronics Interface

2025-06-24

Miaoyi Xu , Zewan Lin , Xiaoling Tong +2 more | Advanced Materials

Abstract The tissue–electronics interface is key to ensuring the effectiveness and stability of medical devices in vivo. Biomaterial‐based fibrous implantable probes represent immense potential in the human tissue–electronics interface, owing … Abstract The tissue–electronics interface is key to ensuring the effectiveness and stability of medical devices in vivo. Biomaterial‐based fibrous implantable probes represent immense potential in the human tissue–electronics interface, owing to their unique high aspect ratio structural feature, distinguishing flexibility, biocompatibility, and biodegradability. This review elucidates the distinctive characteristics of fibrous probes, highlighting their advantages in terms of adaptability, mechanical compliance, and biocompatibility, making them particularly suitable for implantable applications. The design requirements for implantable fibrous probes are thoroughly analyzed, with a comprehensive summary of their preparation, modification, and assembly techniques. Furthermore, their diverse applications, including electrophysiology, chemical sensing, and optogenetics, are explored to highlight their clinical significance and relevance. The latest advancements in fibrous probes are also reviewed, emphasizing the ongoing challenges in improving long‐term stability, enhancing functionality, and achieving large‐scale fabrication. By addressing these challenges, biomaterial‐based fibrous probes hold the potential to deliver transformative solutions to the current limitations in biomedical technology, paving the way for innovative clinical applications.

Pickering Emulsion-Driven MXene/Silk Fibroin Hydrogels with Programmable Functional Networks for EMI Shielding and Solar Evaporation

2025-06-24

Guang Yin , Jing Wu , Cheng-Zhang Qi +3 more | Nano-Micro Letters

Abstract Flexible and conformable nanomaterial-based functional hydrogels find promising applications in various fields. However, the controllable manipulation of functional electron/mass transport networks in hydrogels remains rather challenging to realize. We … Abstract Flexible and conformable nanomaterial-based functional hydrogels find promising applications in various fields. However, the controllable manipulation of functional electron/mass transport networks in hydrogels remains rather challenging to realize. We describe a general and versatile surfactant-free emulsion construction strategy to customize robust functional hydrogels with programmable hierarchical structures. Significantly, the amphipathy of silk fibroin (SF) and the reinforcement effect of MXene nanosheets produce sable Pickering emulsion without any surfactant. The followed microphase separation and self-cross-linking of the SF chains induced by the solvent exchange convert the composite emulsions into high-performance hydrogels with tunable microstructures and functionalities. As a proof-of-concept, the controllable regulation of the ordered conductive network and the water polarization effect confer the hydrogels with an intriguing electromagnetic interference shielding efficiency (~ 64 dB). Also, the microstructures of functional hydrogels are modulated to promote mass/heat transfer properties. The amino acids of SF and the surface terminations of MXene help reduce the enthalpy of water evaporation and the hierarchical structures of the hydrogels accelerate evaporation process, expecting far superior evaporation performance (~ 3.5 kg m⁻ 2 h⁻ 1 ) and salt tolerance capability compared to other hydrogel evaporators. Our findings open a wealth of opportunities for producing functional hydrogel devices with integrated structure-dependent properties.

Bistable Multi‐Layer Triboelectric Nanogenerator for Harvesting Random and Ultra‐Low‐Frequency Vibration Energy with Increased Charge Transfer

2025-06-24

Yi Guan , Xin Li , Zhenglun Alan Wei +5 more | Advanced Science

Approximately 70% of the Earth's surface is covered by seawater, making the ocean ideal for harvesting energy. Triboelectric nanogenerators (TENGs), due to their low cost and simple structure, are well-suited … Approximately 70% of the Earth's surface is covered by seawater, making the ocean ideal for harvesting energy. Triboelectric nanogenerators (TENGs), due to their low cost and simple structure, are well-suited for capturing ocean energy. However, their low charge transfer under weak inputs limits efficiency in harvesting random and ultra-low-frequency wave energy. This paper proposes a novel bistable multi-layer TENG (BM-TENG) to address this challenge for self-powered wireless sensing and lighting. Simulations and experiments demonstrate that both in intra-well and inter-well motions, the bistable mechanism enhances the dynamic responses and thus the power output by up to 48%. Furthermore, the multi-layer design within the constrained structure significantly boosts the power density. Experimental results show 730 V peak-to-peak open-circuit voltage and 5 mW maximum power in a three-layer BM-TENG under the excitation of 0.6 Hz and 0.18 g. The normalized power density of the proposed device is 54.9 Wm-3·Hz-1, surpassing the state-of-the-art results in literature. The application test shows that BM-TENG can successfully power 296 LEDs for ocean warning lighting, and power Bluetooth wireless sensors for monitoring marine environmental variables. This work introduces a novel and highly efficient self-powered sensing technique for advancements in marine Internet of Things (IoT) systems.

Ultrasensitive Force-and-Wind Dual-Mode Biomimetic Sensor Based on Mimosa-Motivated Tb@HOF Photoexcited Foam for Artificial Intelligence-Assisted Human Health Monitoring

2025-06-24

Kai Zhu , Bing Yan | Analytical Chemistry

Nowadays, developing highly efficient and sensitive flexible optical biomimetic devices for the sensing of physical stimulus still has great challenges. Mimosa, as a sensitive plant, can respond to stimuli, such … Nowadays, developing highly efficient and sensitive flexible optical biomimetic devices for the sensing of physical stimulus still has great challenges. Mimosa, as a sensitive plant, can respond to stimuli, such as touch force and wind blowing with leaf movements. Enlightened by this perception function, a force-wind dual-mode flexible optical biomimetic sensor (Tb@HOF-TMBTI@PF) is designed based on the assembly of a hydrogen-bonded organic framework (Tb@HOF-TMBTI) with a foam carrier. As a force sensor, Tb@HOF-TMBTI@PF possesses a great force-release elasticity ability, endowing it with excellent maximum sensitivity (18.98 kPa-1), ultralow minimum detection limit (DL, 0.8 Pa), and ultrafast response/recovery time (60 ms). In the wind sensing process, Tb@HOF-TMBTI@PF exhibits a multiangle recognition response (0°-180°), good repeatability (600 cycles), ultralow DL (0.0038 m s-1), and high precision. By finite element simulation, both the force and wind sensing processes are analyzed in depth. Morse code-assisted patient breathing and contact force dual-channel information expression is materialized. Moreover, by means of artificial intelligence technology, this sensor can evaluate the function and health status of the human respiratory system. This work promotes the development of luminescent force-wind sensing technology with high performances, establishing a solid foundation to develop intelligent multifunctional healthcare equipment for emerging and transformative remote medical diagnosis.

Fabrication and Characterization of a PZT-Based Touch Sensor Using Combined Spin-Coating and Sputtering Methods

2025-06-24

Melih Özden , Ömer Çoban , Tevhit Karacalı | Sensors

This study presents the successful fabrication of lead zirconate titanate (PZT) thin films on silicon (Si) substrates using a hybrid deposition method combining spin-coating and RF sputtering techniques. Initially, a … This study presents the successful fabrication of lead zirconate titanate (PZT) thin films on silicon (Si) substrates using a hybrid deposition method combining spin-coating and RF sputtering techniques. Initially, a PZT layer was deposited through four successive spin-coating cycles, followed by an additional layer formed via RF sputtering. The resulting multilayer structure was annealed at 700 ∘C for 2 h to improve crystallinity. Comprehensive material characterization was conducted using XRD, SEM, cross-sectional SEM, EDX, and UV–VIS absorbance spectroscopy. The analyses confirmed the formation of a well-crystallized perovskite phase, a uniform surface morphology, and an optical band gap of approximately 3.55 eV, supporting its suitability for sensing applications. Building upon these findings, a multilayer PZT-based touch sensor was fabricated and electrically characterized. Low-frequency I–V measurements demonstrated consistent and repeatable polarization behavior under cyclic loading conditions. In addition, |Z|–f measurements were performed to assess the sensor’s dynamic electrical behavior. Although expected dielectric responses were observed, the absence of distinct anti-resonance peaks suggested non-idealities linked to Ag+ ion diffusion from the electrode layers. To account for these effects, the classical Butterworth–Van Dyke (BVD) equivalent circuit model was extended with additional inductive and resistive components representing parasitic pathways. This modified model provided excellent agreement with the measured impedance and phase data, offering deeper insight into the interplay between material degradation and electrical performance. Overall, the developed sensor structure exhibits strong potential for use in piezoelectric sensing applications, particularly for tactile and pressure-based interfaces.

Unlock multi-function: Cnts@COF hydrogel with high toughness, arbitrary shape adaptability, strong electromagnetic shielding and heat insulation performance

2025-06-24

Kunlan Diao , Teng Zhou , Daohai Zhang +4 more | Progress in Organic Coatings

Zwitterionic Surfactant Enhanced Stable Hydrogels for Epidermal Sensors and External Contact Object Perception

2025-06-24

Wei Xu , Yuzhe Gu , Wenjie Xia +6 more | ACS Sensors

Hydrogel-based epidermal sensors are highly valued for their flexibility, biocompatibility, and ability to monitor physiological signals with high fidelity. However, their widespread application has been hindered by challenges related to … Hydrogel-based epidermal sensors are highly valued for their flexibility, biocompatibility, and ability to monitor physiological signals with high fidelity. However, their widespread application has been hindered by challenges related to stability and low conductivity, which can degrade performance over time. In this study, we present a novel approach to enhance both the stability and conductivity of hydrogels while maintaining biocompatibility by incorporating betaine (BA) into ionically conductive acrylamide (AA) and poly(2-acryloylamino-2-methyl-1-propanesulfonic acid) (AMPS) hydrogel matrices. The incorporation of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) addresses the conductivity reduction caused by excessive BA, restoring high ionic conductivity (∼0.84 S m-1) of the hydrogel. As a result, the hydrogel demonstrates excellent stability, retaining 78% of its weight after 14 days, while maintaining exceptional electrical, mechanical (∼18.13 kPa tensile strength, ∼450% elongation), and adhesive (∼4.01 kPa) properties. This optimized hydrogel enables reliable epidermal sensing, ensuring high-quality electrophysiological signal acquisition (signal-to-noise ratio ∼ 25 dB) unaffected by motion artifacts and achieving 97.5% accuracy in external object contact sensing, presenting a promising solution for the development of advanced wearable electronics.

Sandwich‐Structured hBN/BT‐VTS/PVDF‐HFP Nanocomposites with Solid and Interconnected Porous Central Layers as Flexible Piezoelectric Energy Harvesters for Self‐Powered Wearable Electronics: Enhanced Breakdown Strength and Power Density by Tailoring Structural Design

2025-06-24

Levent Köroğlu , Carmen R. Tubío , Erhan Ayas +2 more | Energy Technology

Sandwich‐structured poly(vinylidene fluoride)‐co‐hexafluoropropylene (PVDF‐HFP) matrix nanocomposites with solid and interconnected porous central layers are prepared by hot pressing to investigate the structural design's role on their dielectric properties, energy storage, … Sandwich‐structured poly(vinylidene fluoride)‐co‐hexafluoropropylene (PVDF‐HFP) matrix nanocomposites with solid and interconnected porous central layers are prepared by hot pressing to investigate the structural design's role on their dielectric properties, energy storage, and energy harvesting performances. Solid monolayered nanocomposites reinforced with 4 wt% hexagonal boron nitride (hBN) nanoparticles (NPs) and solid and porous monolayered nanocomposites incorporated with 25 wt% silane‐modified BaTiO 3 NPs (BT‐VTS) are located in outer and central layers, respectively, to achieve the BN‐BT‐BN configuration. Despite the low energy storage performances (discharged energy densities) of sandwich structures, the charge‐blocking hBN/PVDF‐HFP nanocomposites at the outer layers of the solid sandwiches enhance the breakdown strength of solid monolayered BT‐VTS/PVDF‐HFP nanocomposites ( E b : 271 MV m −1 ) by 23%. On the other hand, piezoelectric output voltages of the porous monolayer and sandwich structures (1.7 and 1.1 V) are 6 and 3 times those of their solid counterparts, respectively, under finger bending at 1 Hz. This indicates a significant impact of structural design on the energy harvesting performance, which is considerably improved by a 3D pore network. Therefore, porous sandwich‐structured 4% hBN/25% BT‐VTS/PVDF‐HFP nanocomposites with an enhanced power density of 22.11 μW cm −3 have the capability to be used as flexible piezoelectric nanogenerators in self‐powered wearable devices.

Supramolecular Polyelectrolyte Film for Spontaneous Electricity Generation with Photoresponsive Output Signals and Intrinsic Recyclability

2025-06-24

Haiqi Zhang , Yiting Feng , Ka-Po Maggie Tang +1 more | Chemistry - A European Journal

Developing recyclable polymeric films for spontaneous power generation with stimuli‐responsive output signals is a significant step towards sustainable wearable sensors, fashion textiles, etc., which remains highly challenging. Herein, we developed … Developing recyclable polymeric films for spontaneous power generation with stimuli‐responsive output signals is a significant step towards sustainable wearable sensors, fashion textiles, etc., which remains highly challenging. Herein, we developed polyelectrolyte films for moisture‐sorption‐based electricity generation with photoresponsive electrical output signals from supramolecular co‐assembly of alkaline solutions of lipoic acid (LA) and hyaluronic acid (HA) with amphiphilic azobenzene dopant and ionic liquid via an evaporation‐induced polymerization process. Due to the intrinsic hygroscopic property and layer‐by‐layer structure with water channels, the corresponding polyelectrolyte films can absorb ambient moisture to induce charged ions dissociation and ion flow in the water channels, enabling spontaneous electricity generation. The polyelectrolyte film (0.4 cm × 1.5 cm) generated currents up to 11.8 nA at ambient conditions (21.6 °C and 69% RH). Notably, an immediate increase of current signal was observed by exposure to UV light because of variations in molecular geometry and polarity of the azobenzene dopant between trans and cis isomers. Besides, the polyelectrolyte films were easily recycled by dissolving in water and subsequent re‐evaporation. The results demonstrated a new and simple pathway for developing recyclable supramolecular materials featuring spontaneous electricity generation with photoresponsive output signals, providing attractive opportunities for future sustainable advanced materials.

Formulation and Process for Air Stable Zn‐Based Printed Flexible Electronics

2025-06-23

Naveed ul Hassan Alvi , Valerio Beni , Jesper Edberg | Advanced Sustainable Systems

Abstract This article presents a novel, high‐performance, screen‐printable zinc (Zn)‐based ink and a chemical sintering process that significantly improves long‐term air stability. The ink formulation combines micro‐ and nanoparticles, enhancing … Abstract This article presents a novel, high‐performance, screen‐printable zinc (Zn)‐based ink and a chemical sintering process that significantly improves long‐term air stability. The ink formulation combines micro‐ and nanoparticles, enhancing electrical conductivity—up to 10 times compared to microparticle‐only inks. Micro‐fibrillated cellulose (Exilva) is used as a sustainable binder, aligning with eco‐friendly electronics initiatives. Besides the formulation, the benefit of a multistep chemical sintering approach, based on the sequential immersion of the printed structures in acetic acid solution, is demonstrated. If with a more conventional one‐step acetic acid sintering treatment a conductivity of ≈3.18 × 10⁵ S m − ¹ can be achieved, the use of the multi‐step process further enhances both conductivity, increasing conductivity ≈2.6 times to ≈8.37 × 10⁵ S m − ¹ (sheet resistance 0.06 Ω □ − ¹), it is the highest reported value achieved through chemical sintering—just 20 times lower than bulk Zn (≈16.6 × 10⁶ S m − ¹). Importantly, the ink, following the proposed chemical sintering and without encapsulation also exhibits outstanding air stability, maintaining functionality with only an ≈11% increase in resistance after 6 months in ambient conditions (40–60% RH). By offering superior durability, flexibility, and, most notably, unprecedented air stability, this Zn‐based ink presents a significant advancement for sustainable and flexible electronics.

A cantilever sensor for skin friction measurement in hypersonic flows

2025-06-23

Shamim Pathan , Maitri Kshetrimayum , Viren Menezes +1 more | Sadhana

Electronic Waste to Energy: Self‐Powered Electronic Devices and Organic Dye Degradation Using TENG‐Assisted Photocatalysis

2025-06-23

Anusha Kaki , Gouranga Maharana , Navaneeth Madathil +4 more | Advanced Sustainable Systems

Abstract Electronic waste (e‐waste) and the use of portable electronic devices are rapidly increasing due to technological advancements globally, leading to harmful effects on the environment. E‐waste causes severe environmental … Abstract Electronic waste (e‐waste) and the use of portable electronic devices are rapidly increasing due to technological advancements globally, leading to harmful effects on the environment. E‐waste causes severe environmental damage, such as the pollution of soil, water, and air. Therefore, there is an urge for effective e‐waste management, recycling, and sustainable consumption. In this report, We developed high‐performance triboelectric nanogenerators (TENGs) utilizing discarded laptop LCD screens as triboelectric layers for energy harvesting and organic dye pollutant degradation. Among all the fabricated devices, the LCDW4‐TENG exhibited exceptional performance with fluorinated ethylene propylene (FEP) as the opposite frictional layer, yielding a V oc of ≈470 V, I sc of ≈ 143 µA, and a power density of 5.04 W m − 2 at a load resistance of 1 MΩ. The long‐term stability of the device is tested over 6,000 cycles and is found to be very stable. This e‐waste‐based TENG is employed in the treatment of methylene blue organic dye through TENG‐assisted photocatalysis. An enhanced degradation efficiency of methylene blue dye is observed with the support of TENG. This work highlights the potential of LCD waste‐derived TENGs for driving self‐powered electronic devices and environmental remediation applications thereby contributing to the circular economy concept.

Sweat Wearable Sensor Based on Confined Pt Nanoparticles in 2D Conductive Metal–Organic Frameworks for Continuous Glucose Monitoring

2025-06-23

Wei Huang , Yong Yang , Yun Xu +2 more | Advanced Science

Abstract The noninvasive glucose sensors with comprehensive functional capabilities can enable wearable glucose monitoring in sweat with high sensitivity and minimal risk. However, the limited stability of natural enzymes, along … Abstract The noninvasive glucose sensors with comprehensive functional capabilities can enable wearable glucose monitoring in sweat with high sensitivity and minimal risk. However, the limited stability of natural enzymes, along with interference from electro‐oxidizable species, continues to pose significant challenges for their long‐term application. Herein, an integrated wearable system is presented for nonenzymatic glucose monitoring in sweat at the point of care. This system integrates a flexible microfluidic glucose sensor patch for sweat sampling and measurement, using Pt nanoparticles (Pt‐NPs) confined within phthalocyanine‐based conductive metal–organic frameworks (Pc‐MOFs) as electrode materials, and a flexible printed circuit board for signal/analysis and wireless communication. The microfluidic sensor patch based on Pc‐MOFs confined Pt‐NPs exhibits significantly improved nonenzymatic glucose sensing performances. This is attributed to the ultrasmall size of Pt‐NPs and the confinement effect within the Pc‐MOF channels, which regulates the glucose adsorption intensity and increases the electrocatalytic activity to glucose oxidation. During the continuous monitoring process, the glucose concentration is calibrated in sweat by accounting for fluctuations in pH and temperature, and evaluated the performance of the wearable device in monitoring sweat glucose levels in human subjects over a 12‐h period, achieving data as accurate as that obtained using high‐performance liquid chromatography.

Materials design and integration strategies for soft bioelectronics in digital healthcare

2025-06-23

Hye Jin Kim , Ja Hoon Koo , Seunghwan Lee +2 more | Nature Reviews Materials

Flexible Microinterventional Sensors for Advanced Biosignal Monitoring

2025-06-23

Ying Liu , Peidi Fan , Yuxiang Pan +1 more | Chemical Reviews

Flexible microinterventional sensors represent a transformative technology that enables the minimal intervention required to access and monitor complex biosignals (e.g., bioelectrical, biophysical, and biochemical signals) originating from deep tissues, thereby … Flexible microinterventional sensors represent a transformative technology that enables the minimal intervention required to access and monitor complex biosignals (e.g., bioelectrical, biophysical, and biochemical signals) originating from deep tissues, thereby providing accurate data for diagnostics, robotics, prosthetics, brain-computer interfaces, and therapeutic systems. However, fully unlocking their potential hinges on establishing a nondisruptive, intimate, and nonrestrictive interface with the tissue surface, facilitating efficient integration between the microinterventional sensor and the target tissue. In this comprehensive review, we highlight the critical tissue characteristics in both physiologically and pathologically relevant contexts that are pivotal for the design of microinterventional sensors. We also summarize recent advancements in flexible substrate materials and conductive materials, which are tailored to facilitate effective information interaction between bioelectronic components and biological tissues. Furthermore, we classify various electrode architectures─spanning 1D, 2D, and 3D─designed to accommodate the mechanics of soft tissues and enable nonrestrictive interfaces in diverse sensing scenarios. Additionally, we outline critical challenges for next-generation microinterventional sensors and propose integrating advanced materials, innovative fabrication, and embedded intelligence to drive breakthroughs in biosignal sensing. Ultimately, we aim to both provide foundational understanding and highlight emerging strategies in biosignal capture, leveraging recent advancements in these critical components.

Intrinsically Stretchable Electroluminescent Elastomers Based on Fully Conjugated Backbones for Organic Light-Emitting Diodes

2025-06-23

Yi Wan , Haotian Yuan , Qianwei Xu +5 more | Macromolecules

Stretchable, Highly Sensitive Dual-Network Ionic Organic Hydrogel for Wearable Flexible Sensors and Supercapacitors

2025-06-23

Lingling Meng , Da Liu , En Liu +1 more | ACS Applied Electronic Materials

Direct Characterization of Mechanical Properties in Fully Free-Standing Polymeric Electronic Films for Stretchable Devices

2025-06-23

Jintao Feng , Saimeng Li , Chunlong Sun +2 more | Macromolecules

Investigation and optimization of the piezoelectric nanocomposite ZnO/PVVH/P(VDF-TrFE) for energy harvesting applications

2025-06-23

Afaf Sarhan , A. K. Hassan , Mahmoud Abdelhamid +2 more | Scientific Reports

Sea Cucumber Physiology of Liquid Metal Flexible Electronics with High Mechanical Stability and Curvature Conformity via Electroplating

2025-06-23

Haoqin Ma , Ge Wang , Xia Sheng +7 more | ACS Applied Materials & Interfaces

The inherent rigidity of traditional printed circuit boards (PCBs) imposes significant limitations on device deformability, rendering them inadequate for the evolving demands of lightweight, flexible, and highly deformable electronic systems. … The inherent rigidity of traditional printed circuit boards (PCBs) imposes significant limitations on device deformability, rendering them inadequate for the evolving demands of lightweight, flexible, and highly deformable electronic systems. Although flexible printed circuits (FPCs) offer partial improvements, they continue to face critical challenges including limited mechanical flexibility, insufficient durability, and the absence of intrinsic self-healing capabilities. Drawing inspiration from the adaptive deformation, exceptional flexibility, and autonomous self-healing properties observed in sea cucumbers, this study explores the incorporation of liquid metal (LM) into a flexible circuit design. We propose an electroplating-assisted patterning technique to fabricate LM alloy thin films, addressing key limitations of LM such as high surface tension, poor substrate adhesion, low manufacturing efficiency, and high production costs. Through interfacial energy manipulation, this technique effectively attenuates the intrinsic surface tension of the LM, thereby allowing for spatially selective wetting and strong interfacial bonding with deformable substrate materials. The proposed approach achieves high-resolution patterning down to 40 μm and demonstrates excellent electrical stability, maintaining performance after 10,000 fatigue bending cycles at a curvature radius of 0.5 mm. This work presents a promising technological advancement that not only enhances the functional robustness of flexible electronics but also broadens their potential for practical and scalable applications.

Polypyrrole/Polydimethylsiloxane Sponge-Based Flexible Pressure Sensors with Enhanced Sensitivity and a Wide Detection Range Using Programmable Gradient Pore Density

2025-06-23

Byungkwon Chun , Junyoung Park , Joohyung Bang +3 more | ACS Applied Electronic Materials

Self‐Powered Real‐Time Temperature Sensing Based on Flexible Ionic Elastomer on Triboelectric Nanogenerators

2025-06-23

Hee Jae Hwang , Joo Sung Kim , Seungin Oh +7 more | Advanced Functional Materials

Abstract Self‐powered flexible thermal‐management systems have garnered interests in wearable electronic devices and AI semiconductors. However, their efficiency and reliability remain limited in practical applications. In this study, an ionic … Abstract Self‐powered flexible thermal‐management systems have garnered interests in wearable electronic devices and AI semiconductors. However, their efficiency and reliability remain limited in practical applications. In this study, an ionic temperature‐sensing triboelectric nanogenerator (iTS‐TENG) is proposed with an ionic elastomer containing thermoplastic polyurethane (TPU) and ionic liquids (ILs). The TPU matrix undergoes deformation of microphase separation by thermal stimulation near the glass transition temperature. Furthermore, ILs facilitate the formation of electrical double layers as charge carriers and enhance the thermal sensitivity as heat carriers under mechanical and thermal stimuli. Thus, iTS‐TENG demonstrates enhanced outputs (734 V) and high thermal sensitivity (3.87 V/°C) from room temperature to 70 °C, with fast response time and reproducibility (more than 20 cycles). Finally, real‐time and self‐powered iTS‐TENG is demonstrated, showing that the sensed temperature is comparable to a commercial temperature sensor. These results indicate that iTS‐TENG is suitable for thermal‐management applications in self‐powered wearable electronic systems.

CaTiO3/ZnO‐PVDF Composite‐Based Triboelectric Nanogenerators for Self‐Powered Gait Sensing

2025-06-23

Xin Jia , Xiaobo Wu , Long Qi +4 more | Advanced Functional Materials

Abstract In the context of the ongoing development of artificial intelligence and 5G technologies, a growing number of sensors are being integrated into the daily lives. Self‐powered wearable sensors based … Abstract In the context of the ongoing development of artificial intelligence and 5G technologies, a growing number of sensors are being integrated into the daily lives. Self‐powered wearable sensors based on triboelectric nanogenerator (TENG) represent an innovative solution to this trend, but the output performance of the flexible TENGs remains suboptimal. In this study, the band‐matched calcium titanate (CaTiO 3 ) and zinc oxide (ZnO) nanostructures are prepared to form CaTiO 3 /ZnO (CTO/ZnO) Schottky heterojunctions. The heterojunctions are subsequently doped into organic ferroelectric polyvinylidene fluoride (PVDF) to create flexible composite film, which significantly increases the dielectric constant through space charge polarization. Then the CTO/ZnO‐PVDF composite films served as triboelectric materials of the CaTiO 3 /ZnO‐PVDF‐based TENG (CZP‐TENG). After optimizing the molar ratio of ZnO to CTO in heterojunction and weight ratio of CTO/ZnO in PVDF, both the output voltage and current density of the TENG are significantly improved, exhibiting a power density of 106.6 mW m −2 . Finally, the CZP‐TENG powers light–emitting diodes and a temperature sensor, serves as a wearable sensor, and enables self‐powered human body sensing, particularly in gait recognition for preventing of movement‐related diseases and injury rehabilitation.

Nature-Inspired Bioelectric Stimuli-Based Electroactive Polymeric Therapeutics Technology for Osteoarthritis Treatment─A Review

2025-06-22

Preethi Hegde , Anjaneyulu Udduttula | ACS Biomaterials Science & Engineering

The self-healing capacity of severely damaged articular cartilage is inherently limited due to weak cellular signaling, low cell turnover, poor extracellular matrix synthesis, and a lack of vascularization. Such damage … The self-healing capacity of severely damaged articular cartilage is inherently limited due to weak cellular signaling, low cell turnover, poor extracellular matrix synthesis, and a lack of vascularization. Such damage to cartilage can lead to severe pain and the progression of osteoarthritis, significantly impacting patients' physical and mental well-being. Current surgical and nonsurgical interventions for repairing and regenerating cartilage tissue have shown inadequate long-term efficacy. Recently, the intrinsic electrical properties of bone tissue inspired researchers to focus on designing and fabricating regenerative biomaterials with bioelectrical properties such as piezoelectric, pyroelectric, ferroelectric, and dielectric for more effective treatment of bone defects. Among these electrical cues, piezoelectricity, in particular, plays a critical role in fracture healing and joint mechanics. The loss of cartilage alters biomechanics and may disrupt essential mechanotransduction pathways. However, the potential of these piezoelectrically active biomaterials with a combination of electroactive polymeric and biomimetic inorganic materials for regenerating cartilage and alleviating osteoarthritis has not been thoroughly explored. Therefore, developing natural, innovative, and biofunctional biomaterials with electrical properties is imperative to treating osteoarthritis effectively. The advancement of biomaterials with electroactive and other features offers the potential to transmit direct electrical signals to cells and stimulate faster tissue regeneration. In this review, we aim to understand and explore the electroactive properties of polymeric-based biomaterials by analyzing their potential applications and challenges in treating osteoarthritis. Specifically, we discussed how electroactive polymers can serve as bioinks for 3D bioprinting, hydrogels, coatings, and scaffolds in combination with bioactive inorganic materials to repair and regenerate articular cartilage. This comprehensive review will aid researchers in gaining a deeper understanding of electroactive polymers and provide insightful information for the development and advancement of electroactive biomaterials like piezo-activated next-generation biomaterials for the treatment of osteoarthritis in an effective manner.

Stretchable self-sensing conductive hydrogel with tunable photothermal response and actuation capability

2025-06-22

Ping Guo , Yang-Zhang Zhou , Wenjie Cao +7 more | The European Physical Journal Special Topics

Biomimetic Neural Intelligent E-Skin System for Tactile Perception and Robotic Decision-Making

2025-06-22

Deliang Li , Ruiwen Wang , Kexin Fu +7 more | ACS Sensors

The widespread application of electronic skin (e-skin) in human-machine interaction necessitates intelligent and information-rich systems. However, the rapid and efficient deployment of e-skin for high-precision multisensor fusion remains a critical … The widespread application of electronic skin (e-skin) in human-machine interaction necessitates intelligent and information-rich systems. However, the rapid and efficient deployment of e-skin for high-precision multisensor fusion remains a critical challenge. This study introduces a pioneering biomimetic neural intelligent e-skin system that significantly enhances human-machine interaction and robotic perception capabilities. Our innovative approach integrates two novel e-skin technologies: a highly flexible multiwalled carbon nanotube (MWCNT) based e-skin for precise pressure sensing, and a gallium-indium alloy liquid metal e-skin with exceptional stretchability for motion capture. The MWCNT e-skin, fabricated through a simple carbon nanotube impregnation method, achieves ultrathinness (<1 mm), ease of preparation, and inherent flexibility. The liquid metal e-skin, developed using a unique dispersion and reconstruction method, exhibits excellent linearity (R2 > 99.9%) and impressive stretchability (∼700%). By integrating our two types of e-skins, our system has achieved multidegree-of-freedom control and tactile feedback for robotic arms. It demonstrates the capability to perform object grasping tasks solely through tactile feedback in visually challenging environments, including underwater conditions. The system achieves a 98.26% accuracy in identifying diverse objects and making autonomous decisions through tactile sensing alone, showcasing its self-decision-making abilities. This research establishes a new paradigm for intelligent robotics, advancing human-machine interaction in complex environments.

Molecularly Engineered Quaternized κ‐Carrageenan: a Multifunctional Platform for Atmospheric Water Harvesting, Moisture‐Electricity Generation, and Self‐powered Wearable Sensors

2025-06-22

Na Li , Xiao Yu , Da‐Peng Yang +1 more | Advanced Functional Materials

Abstract The pursuit of sustainability in the energy and environmental fields, coupled with the innovation in intelligent wearable sensing technologies, demands high‐performance materials with advanced functionalities. Molecular design has emerged … Abstract The pursuit of sustainability in the energy and environmental fields, coupled with the innovation in intelligent wearable sensing technologies, demands high‐performance materials with advanced functionalities. Molecular design has emerged as a cornerstone for optimizing material properties and achieving multifunctional integration. Natural carrageenan, a green substrate material known for its biocompatibility and renewability, faces challenges due to its limited processability and mechanical robustness. In this study, zwitterionic groups are introduced through molecular design to regulate intermolecular interactions, significantly lowering the sol–gel transition temperature, thus enabling superior processability and enhanced mechanical properties. This modification strategy enables efficient salt ion immobilization, endowing the material with outstanding atmospheric water harvesting (AWH) capabilities (2.1 g g − ¹) and stable moisture‐electricity generation (MEG) performance (0.9 V of V oc ). Leveraging these advancements, a self‐powered smart sensor is developed, capable of real‐time monitoring of respiratory states, pressure sensing, and rapid response to noncontact actions. This work provides an integrated material design framework that facilitates innovation in green energy and personalized health monitoring technologies.

Developing and characterizing a flexible piezoelectric nanogenerator based on PVA/ZnO-Fe using the electrospinning method

2025-06-22

Saliha Rabehi , Malika Saidi , Zakia Chelli +7 more | Polymer-Plastics Technology and Materials

Ultrastretchable, Self-Adhesive, UV-Shielding Conductive Hydrogel as a Flexible Wearable Sensor for Human–Machine Interaction

2025-06-22

Wen Liu , Mingjie Liu , Ying Li +7 more | ACS Applied Materials & Interfaces

Conductive hydrogels are promising candidates for next-generation wearable electronics due to their flexibility, biocompatibility, and ion-conductive properties. However, achieving a balance among electrical conductivity, mechanical robustness, interfacial adhesion, and environmental … Conductive hydrogels are promising candidates for next-generation wearable electronics due to their flexibility, biocompatibility, and ion-conductive properties. However, achieving a balance among electrical conductivity, mechanical robustness, interfacial adhesion, and environmental stability remains a key challenge. Herein, we present a multifunctional hydrogel synthesized via a one-pot free radical polymerization of acrylic acid, methacryloxyethyltrimethylammonium chloride, tannic acid, and calcium ions. The designed hydrogel exhibits ultrastretchability (strain up to 2900%) and strong interfacial adhesion (160.92 kPa) owing to a synergistic cross-linked network formed by hydrogen bonding, ionic complexation, coordination, and covalent interactions. Adhesion capacity remains above 80% after ten peel cycles, indicating persistent interfacial coupling. It exhibits two linear sensitivity regimes, with gauge factors of 1.9 below 300% strain and 2.5 up to 1000%, and maintains stable electrical performance over 300 cycles. Its high ionic conductivity (30.24 mS/cm) supports low-impedance signal transmission, while its intrinsic UV-shielding property, derived from the catechol chemistry of tannic acid, enables reliable outdoor operation. The hydrogel also exhibits a rapid response time of 65 ms, allowing accurate detection of dynamic biomechanical signals. This conductive hydrogel holds great promise for real-time monitoring of human motion and microexpressions, as well as for secure communication applications such as Morse code encryption. This hydrogel design offers a promising route toward next-generation wearable electronics with potential applications in smart healthcare, human-machine interaction, and secure communication.

Self-Healing, Remoldable, and Conductive Starch-Based Dual Reversible Cross-Linking Hydrogels for Strain Sensors

2025-06-22

Kai Lu , Xiaolong He , Dian Burhani +6 more | ACS Applied Materials & Interfaces

Polysaccharide-based hydrogels have been utilized as flexible strain sensors because of their renewability, biocompatibility, and biodegradability. However, their widespread application is hindered by the complexity of their manufacturing processes and … Polysaccharide-based hydrogels have been utilized as flexible strain sensors because of their renewability, biocompatibility, and biodegradability. However, their widespread application is hindered by the complexity of their manufacturing processes and the inevitable degradation of their mechanical properties with repeated use. The introduction of reversible bond chemistry offers the potential to impart self-healing properties to hydrogels, extending their functional lifespan. In this study, we prepared a starch-based conductive hydrogel (starch/poly(vinyl alcohol) (PVA)/cellulose nanocrystals (CNCs)) via a straightforward method using borax as a cross-linking agent. The hydrogel demonstrated improved strength and self-healing property because of the addition of CNCs, which formed dual reversible cross-links with starch and PVA via hydrogen and borate ester bonds. Additionally, the sodium ions (Na+) and borate ions (B(OH)4-) within the network enhanced the electrical conductivity and strain sensitivity of the hydrogel. The resulting hydrogel demonstrated potential for application as a wearable sensor capable of monitoring a range of human movements, sensing handwriting, and enabling Morse code communication. Notably, the hydrogel could be easily remolded at room temperature after being sectioned, highlighting its practical applicability. This work expands the scope of the use of starch-based hydrogels in sustainable wearable sensor technologies.

Bionic Perception of Surface Adhesion via a Magnetized Spring-like Sensor with Axial Stretchability

2025-06-22

Yuanzhe Liang , Biao Qi , Ming Lei +5 more | ACS Nano

Perception of surface adhesion is one essential capability of a human fingertip, which is normally realized by touching the target surface with subsequent skin vibrations. However, such functionality is difficult … Perception of surface adhesion is one essential capability of a human fingertip, which is normally realized by touching the target surface with subsequent skin vibrations. However, such functionality is difficult to realize in flexible sensors and robotic systems due to the challenges in axial stretchability with reliable electrical feedback. In this study, we developed a bionic three-dimensional flexible magnetized spring (3D-FMS) that can quantitatively recognize surface adhesion based on electromagnetic induction. Combined with the laser processing with predefined patterns, we show that a raw flexible cube can be converted to highly stretchable spring-like geometry with excellent bidirectional deformation in axial orientation. Furthermore, the mechanical elongation caused by adhesion is critical for the induced voltage signals, allowing us to establish a model that relates adhesion strength with electrical outputs in a linear behavior. Via optimization of the process parameters, the device exhibits tailored stiffness to modulate the sensing sensitivity and working range on demand. With the established interactive interface, the wearable tests and robotic integration demonstrate the potential of the 3D-FMS for adhesion perception as a human fingertip. We expect that the strategy will offer a valuable reference to explore 3D wearable devices that advances robotic systems with more bionic functions such as stickiness determination.

Smart Leather Using Thermoresponsive Cholesteric Liquid Crystals in Surface Finishing

2025-06-21

Cosmin-Andrei Alexe , Carmen Gaidău , Ioana Stănculescu +2 more | Journal of Natural Fibers

Single- and Multi-Network Hydrogels for Soft Electronics—A Review

2025-06-21

Md Murshed Bhuyan , N. Hasan , Jae-Ho Jeong | Gels

Soft or flexible electronics is a rapidly growing and pioneering research field, as it makes devices comfortable to use, especially in biomedical engineering. Both single- and multi-network hydrogels have diverse … Soft or flexible electronics is a rapidly growing and pioneering research field, as it makes devices comfortable to use, especially in biomedical engineering. Both single- and multi-network hydrogels have diverse applications where the most significant one is in the building of soft electronics, including soft circuits, displays, sensors, batteries, and supercapacitors, electronic storage, electric skin, health monitoring devices, soft robots, and automotive. Three-dimensional printing of conductive gels/hydrogels facilitates the construction of soft electronics. This review illustrates the design, mechanism, and application of hydrogel in soft electronics. The current progress, scope of improvement, and future prospects of hydrogel-based soft electronics are also discussed. This review will provide a clear concept of the topic to researchers.

A Novel pressure sensors fabricated from laser-induced graphene on polyimide film: A step towards advanced wearable technology

2025-06-21

Ghofran Sattar Jabbar , Mariam M. Abud , Mohand M. Azzawi | Journal of Optics

Ceria/ PVDF/PVDF-HFP Nanocomposite: Designing, Characterization, Optical, Piezo- and Pyroelectric Properties for Energy Storage Systems

2025-06-21

A. Habib , T. Fahmy , A. Almalki +1 more | Journal of Inorganic and Organometallic Polymers and Materials

Abstract Poly vinylidene fluoride (PVDF) is blended with poly (vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) via solution-casting technique. Herein, various concentrations of ex-situ synthetic ceria nanoparticles (CeO 2 NPs) were incorporated within … Abstract Poly vinylidene fluoride (PVDF) is blended with poly (vinylidene fluoride-co-hexafluoro propylene) (PVDF-HFP) via solution-casting technique. Herein, various concentrations of ex-situ synthetic ceria nanoparticles (CeO 2 NPs) were incorporated within a (50/50 wt% PVDF/PVDF-HFP) polymeric blend (PB). The prepared ceria nanocomposites were characterized by X- ray diffraction (XRD), Scanning electron microscope (SEM), Fourier transformed infrared (ATR-FTIR) and UV/Vis analysis. XRD and FTIR analysis confirmed that the crystalline electroactive β-phase in the PVDF and PVDF-HFP is enhanced after blending and doping with CeO 2 NPs. UV/Vis analysis showed that both direct and indirect band gaps for nanocomposites films are reduced to be about 3.37 and 3.2 eV, respectively. Thermally stimulated depolarization current (TSDC) measurement of the different relaxation phases with polarization in the corona discharge field for different prepared samples had been obtained. TSDC results of the main β-relaxation peak show an enhancement of the relaxation time (τ) and decrease in activation energy (E a ), which is related to higher regularity of the system structure. The piezo- and pyroelectric activity of the various prepared samples were investigated. Pyroelectric coefficient enhanced to be about ≈ 68.5 µC/m 2 K for 20wt.% CeO 2 /PB. The high piezoelectric coefficient d 33 obtained for 20wt.% CeO 2 /PB was about 37.2 pC/N. This innovative flexible piezoelectric structure emerges as a strongly favorable candidate that can be applied as intelligent stress-responsive materials utilized in various energies harvesting piezoelectric technologies.