The stretchable sensor wrapped around a foldable airfoil or embedded inside of it has great potential for use in the monitoring of the structural status of the foldable airfoil.The design methodology is important to t...The stretchable sensor wrapped around a foldable airfoil or embedded inside of it has great potential for use in the monitoring of the structural status of the foldable airfoil.The design methodology is important to the development of the stretchable sensor for status monitoring on the foldable airfoil.According to the requirement of mechanical flexibility of the sensor,the combined use of a layered flexible structural formation and a strain isolation layer is implemented.An analytical higher-order model is proposed to predict the stresses of the strain-isolation layer based on the shear-lag model for the safe design of the flexible and stretchable sensors.The normal stress and shear stress equations in the constructed structure of the sensors are obtained by the proposed model.The stress distribution in the structure is investigated when bending load is applied to the structures.The numerical results show that the proposed model can predict the variation of normal stress and shear stress along the thickness of the strain-isolation(polydimethylsiloxane)layer accurately.The results by the proposed model are in good agreement with the finite element method,in which the normal stress is variable while the shear stress is invariable along the thickness direction of strain-isolation layer.The high-order model is proposed to predict the stresses of the layered structure of the flexible and stretchable sensor for monitoring the status of the foldable airfoil.展开更多
Vascular endothelium can perceive fluid shear stress(FSS)and cyclic circumferential stretch(CCS)caused by the pulsatile blood flow,and translate the hemodynamics into biochemical signals to regulate vascular pathophys...Vascular endothelium can perceive fluid shear stress(FSS)and cyclic circumferential stretch(CCS)caused by the pulsatile blood flow,and translate the hemodynamics into biochemical signals to regulate vascular pathophysiology.However,existing methods provide little information about the real-time biochemical responses of endothelium when exposed to dynamic FSS and CCS.Herein,a vasculature-on-a-chip integrated with stretchable sensing is engineered for recapitulating the hemodynamic milieus and in-situ monitoring biochemical responses of endothelial monolayer.The integrated device is developed by sandwiching a robust stretchable electrode between an upper fluidic channel and a lower pneumatic channel.The fluidic and pneumatic channels enable the simultaneous recapitulation of both FSS and CCS,and the integrated sensor exhibits excellent cell-adhesive capacity and electrochemical sensing stability even after long-term hemodynamic exposure.These allow real-time monitoring of hemodynamic form-and duration-dependent endothelium responses,and further efficacy investigation about a recommended drug for COVID-19,demonstrating the great potential in vascular disease and drug screening.展开更多
Continuous and quantitative monitoring of knee joint function has clinical value in rehabilitation assessment and the timing of return to play for anterior cruciate ligament injury patients.However,the existing approa...Continuous and quantitative monitoring of knee joint function has clinical value in rehabilitation assessment and the timing of return to play for anterior cruciate ligament injury patients.However,the existing approaches,including clinical examination,arthrometry and inertial solutions,can only be used for qualitative,off-line and low-quality evaluations,respectively.Burgeoning Kirigami stretchable sensors could be a disruptive candidate solution,but they usually suffer from structural buckling issues when used for large strain applications,such as knee joint motion capture where the buckling degrades sensor reliability and repeatability.Here,we propose a buckling-resistant stretchable and wearable sensor for knee joint motion capture.It enables continuous and precise motion signal capture of the knee joint and provides high wearing comfort and reliability.Clinical tests were conducted on 30 patients in the field,tracking data provided by the sensor from their initial hospitalization to later surgery.And the full rehabilitation of one subject was recorded and analyzed.The test results show that our sensor can dynamically assess knee function in real time and recommend the best timing for return to play,which paves the way for personalized and telerehabilitation.展开更多
With the advent of the 5G era and the rise of the Internet of Things,various sensors have received unprecedented attention,especially wearable and stretchable sensors in the healthcare field.Here,a stretchable,self-he...With the advent of the 5G era and the rise of the Internet of Things,various sensors have received unprecedented attention,especially wearable and stretchable sensors in the healthcare field.Here,a stretchable,self-healable,self-adhesive,and room-temperature oxygen sensor with excellent repeatability,a full concentration detection range(0-100%),low theoretical limit of detection(5.7 ppm),high sensitivity(0.2%/ppm),good linearity,excellent temperature,and humidity tolerances is fabricated by using polyacrylamide-chitosan(PAM-CS)double network(DN)organohydrogel as a novel transducing material.The PAM-CS DN organohydrogel is transformed from the PAM-CS composite hydrogel using a facile soaking and solvent replacement strategy.Compared with the pristine hydrogel,the DN organohydrogel displays greatly enhanced mechanical strength,moisture retention,freezing resistance,and sensitivity to oxygen.Notably,applying the tensile strain improves both the sensitivity and response speed of the organohydrogel-based oxygen sensor.Furthermore,the response to the same concentration of oxygen before and after self-healing is basically the same.Importantly,we propose an electrochemical reaction mechanism to explain the positive current shift of the oxygen sensor and corroborate this sensing mechanism through rationally designed experiments.The organohydrogel oxygen sensor is used to monitor human respiration in real-time,verifying the feasibility of its practical application.This work provides ideas for fabricating more stretchable,self-healable,self-adhesive,and high-performance gas sensors using ion-conducting organohydrogels.展开更多
The Design and manufacturing of a noble piezoresistive pressure sensor(PS) for subtle pressures(<1 kPa) were presented. Meanwhile, in the studies conducted in the field of pressure sensors, the measurement of subtl...The Design and manufacturing of a noble piezoresistive pressure sensor(PS) for subtle pressures(<1 kPa) were presented. Meanwhile, in the studies conducted in the field of pressure sensors, the measurement of subtle pressures has received less attention. The limitations in the inherent gauge factor in silicon, have led to the development of polymer and composite resistive sensitive elements. However,in the development of resistance sensing elements, the structure of composite elements with reinforcement core has not been used. The proposed PS had a composite sandwich structure consisting of a nanocomposite graphene layer covered by layers of PDMS at the bottom and on the top coupled with a polyimide(PI) core. Various tests were performed to analyze the PS. The primary design target was improved sensitivity, with a finite-element method(FEM) utilized to simulate the stress profile over piezoresistive elements and membrane deflection at various pressures. The PS manufacturing process is based on Laser-engraved graphene(LEG) technology and PDMS casting. Experimental data indicated that the manufactured PS exhibits a sensitivity of 67.28 mV/kPa for a pressure range of 30-300 Pa in ambient temperature.展开更多
Stretchable strain sensors have great potential for diverse applications including human motion detection,soft robotics,and health monitoring.However,their practical implementation requires improved repeatability and ...Stretchable strain sensors have great potential for diverse applications including human motion detection,soft robotics,and health monitoring.However,their practical implementation requires improved repeatability and stability along with high sensing performances.Here,we utilized spiky vertical graphene(VG)sheets decorated on carbon nanofibers(VG@CNFs)to establish reliable conductive networks for resistive strain sensing.Three-dimensional(3D)VG@CNFs combined with reduced graphene oxide(rGO)sheets were simply coated on stretchable spandex fibers by ultrasonication.Because of the spiky geometry of the VG sheets,VG@CNF and rGO exhibited enhanced interactions,which was confirmed by mode I fracture tests.Due to the robust conductive networks formed by the VG@CNF and rGO hybrid,the fiber strain sensor exhibited a significantly improved strain range of up to 522%(with a high gauge factor of 1358)and stable resistance changes with minimal variation even after 5000 stretching–releasing cycles under a strain of 50%.In addition,the textile strain sensor based on the VG@CNF/rGO hybrid showed even improved repeatability for various strain levels of 10%to 200%,enabling its implementation on leggings for monitoring of squat posture.This study demonstrates the high potential of the 3D VG@CNF for high-performance and reliable stretchable strain sensors.展开更多
Stretchable electronic sensing devices are defining the path toward wearable electronics. High-performance flexible strain sensors attached on clothing or human skin are required for potential applications in the ente...Stretchable electronic sensing devices are defining the path toward wearable electronics. High-performance flexible strain sensors attached on clothing or human skin are required for potential applications in the entertainment,health monitoring, and medical care sectors. In this work,conducting copper electrodes were fabricated onpolydimethylsiloxane as sensitive stretchable microsensors by integrating laser direct writing and transfer printing approaches. The copper electrode was reduced from copper salt using laser writing rather than the general approach of printing with pre-synthesized copper or copper oxide nanoparticles. An electrical resistivity of 96 l X cm was achieved on 40-lm-thick Cu electrodes on flexible substrates. The motion sensing functionality successfully demonstrated a high sensitivity and mechanical robustness.This in situ fabrication method leads to a path toward electronic devices on flexible substrates.展开更多
Breathing is an inherent human activity;however,the composition of the air we inhale and gas exhale remains unknown to us.To address this,wearable vapor sensors can help people monitor air composition in real time to ...Breathing is an inherent human activity;however,the composition of the air we inhale and gas exhale remains unknown to us.To address this,wearable vapor sensors can help people monitor air composition in real time to avoid underlying risks,and for the early detection and treatment of diseases for home healthcare.Hydrogels with three-dimensional polymer networks and large amounts of water molecules are naturally flexible and stretchable.Functionalized hydrogels are intrinsically conductive,self-healing,self-adhesive,biocompatible,and room-temperature sensitive.Compared with traditional rigid vapor sensors,hydrogel-based gas and humidity sensors can directly fit human skin or clothing,and are more suitable for real-time monitoring of personal health and safety.In this review,current studies on hydrogel-based vapor sensors are investigated.The required properties and optimization methods of wearable hydrogel-based sensors are introduced.Subsequently,existing reports on the response mechanisms of hydrogel-based gas and humidity sensors are summarized.Related works on hydrogel-based vapor sensors for their application in personal health and safety monitoring are presented.Moreover,the potential of hydrogels in the field of vapor sensing is elucidated.Finally,the current research status,challenges,and future trends of hydrogel gas/humidity sensing are discussed.展开更多
Today,the vast majority of microelectromechanical system(MEMS)sensors are mechanically rigid and therefore suffer from disadvantages when used in intimately wearable or bio-integrated applications.By applying new engi...Today,the vast majority of microelectromechanical system(MEMS)sensors are mechanically rigid and therefore suffer from disadvantages when used in intimately wearable or bio-integrated applications.By applying new engineering strategies,mechanically bendable and stretchable MEMS devices have been successfully demonstrated.This article reviews recent progress in this area,focusing on high-performance flexible devices based on inorganic thin films.We start with the common design and fabrication strategies for flexibility and stretchability,summarize the recent application-oriented flexible devices,and conclude with criteria and opportunities for the future development of flexible MEMS sensors.展开更多
Respiratory monitoring plays a pivotal role in health assessment and provides an important application prospect for flexible humidity sensors.However,traditional humidity sensors suffer from a trade-off between deform...Respiratory monitoring plays a pivotal role in health assessment and provides an important application prospect for flexible humidity sensors.However,traditional humidity sensors suffer from a trade-off between deformability,sensitivity,and transparency,and thus the development of high-performance,stretchable,and low-cost humidity sensors is urgently needed as wearable electronics.Here,ultrasensitive,highly deformable,and transparent humidity sensors are fabricated based on cost-effective polyacrylamide-based double network hydrogels.Concomitantly,a general method for preparing hydrogel films with controllable thickness is proposed to boost the sensitivity of hydrogel-based sensors due to the extensively increased specific surface area,which can be applied to different polymer networks and facilitate the development of flexible integrated electronics.In addition,sustainable tapioca rich in hydrophilic polar groups is introduced for the first time as a second cross-linked network,exhibiting excellent water adsorption capacity.Through the synergistic optimization of structure and composition,the obtained hydrogel film exhibits an ultrahigh sensitivity of 13,462.1%/%RH,which is unprecedented.Moreover,the hydrogel film-based sensor exhibits excellent repeatability and the ability to work normally under stretching with even enhanced sensitivity.As a proof of concept,we integrate the stretchable sensor with a specially designed wireless circuit and mask to fabricate a wireless respiratory interruption detection system with Bluetooth transmission,enabling real-time monitoring of human health status.This work provides a general strategy to construct high-performance,stretchable,and miniaturized hydrogel-based sensors as next-generation wearable devices for real-time monitoring of various physiological signals.展开更多
With the fast-evolving landscape of flexible and wearable electronics,functional fibers for withstanding high strains in smart wearables,soft robotics,and health monitoring systems are under increasing demands.We repo...With the fast-evolving landscape of flexible and wearable electronics,functional fibers for withstanding high strains in smart wearables,soft robotics,and health monitoring systems are under increasing demands.We report ultra-stretchable and conductive fibers with a thermal drawing process,controlled and engineered for precise motion sensing.This approach enables uniform fibers with microcavities,facilitating scalable production of elastic and functional fibers through a simple fabrication process.Integrating liquid metal(Eutectic Gallium-Indium-Tin alloys)into the elastic fiber yielded a device with a high gauge factor(GF)of 0.91,remarkable linearity(R^(2)=0.999),rapid response time(100 ms),and low hysteresis(<3%)up to 1000% strain.The SFCSS could be readily integrated into textiles,such as gloves and clothing,enabling detection of a wide range of human motions,including static sensing of finger motion,knee posture and dynamic activities of standing,sitting,squatting,walking,and running.Additionally,the SFCSS demonstrated effectiveness in measuring boundary-lengths of irregular objects,supporting applications in soft robotics.The ultra-stretchable capacitive strain sensor developed in this work provides a new approach to enable wearable electronics and smart textiles for the upcoming era of interactive human-machine interfaces and digital healthcare.展开更多
Flexible strain sensors exhibit outstanding advantages in terms of sensitivity and stability by detecting changes in physical signals.It can be easily attached to human skin and clothed to achieve monitoring of human ...Flexible strain sensors exhibit outstanding advantages in terms of sensitivity and stability by detecting changes in physical signals.It can be easily attached to human skin and clothed to achieve monitoring of human motion and health.However,general sensing material shows low stretchability and cannot respond to signals under large deformation.In this work,a highly stretchable polymer composite was developed by adding small amount(0.17 wt.%)of silver nanowires(AgNWs)in stretchable conductive polymer materials.The conductivity of polymer/AgNWs composite is 1.3 S/m with the stretchability up to 500%.The stretchable strain sensor based on the polymer/AgNWs composite can respond to strain signals in real time,even for 1%strain response,and shows excellent stability over 1,000 loading/unloading cycles.Moreover,the strain sensor can be attached to human skin and clothed to monitor joints,throat and pulse of the human body.The human body electrocardiogram(ECG)signal was detected successfully with the polymer/AgNWs electrode,which is comparable to the signal obtained by the commercial electrode.Overall,the sensors enable monitoring of human movement and health.These advantages make it a potential application in wearable devices and electronic skin.展开更多
Growing health awareness triggers the public's concern about health problems. People want a timely and comprehensive picture of their condition without frequent trips to the hospital for costly and cumbersome gene...Growing health awareness triggers the public's concern about health problems. People want a timely and comprehensive picture of their condition without frequent trips to the hospital for costly and cumbersome general check-ups. The wearable technique provides a continuous measurement method for health monitoring by tracking a person's physiological data and analyzing it locally or remotely.During the health monitoring process,different kinds of sensors convert physiological signals into electrical or optical signals that can be recorded and transmitted, consequently playing a crucial role in wearable techniques. Wearable application scenarios usually require sensors to possess excellent flexibility and stretchability. Thus, designing flexible and stretchable sensors with reliable performance is the key to wearable technology. Smart composite hydrogels, which have tunable electrical properties, mechanical properties, biocompatibility, and multi-stimulus sensitivity, are one of the best sensitive materials for wearable health monitoring. This review summarizes the common synthetic and performance optimization strategies of smart composite hydrogels and focuses on the current application of smart composite hydrogels in the field of wearable health monitoring.展开更多
Large deformability and high sensitivity is difficult to be realized simultaneously in flexible sensors.Herein,taking advantage of the high permittivity and highly active surfaces of the ultrasmall barium titanate nan...Large deformability and high sensitivity is difficult to be realized simultaneously in flexible sensors.Herein,taking advantage of the high permittivity and highly active surfaces of the ultrasmall barium titanate nanoparticles(BT NPs)and the high stretchability of the p(BA-GMA)elastomer matrix,we propose a high-performance soft stretchable sensor.The addition of the ultrasmall BT NPs can not only increase the permittivity and capacitance of polyacrylate-matrix composite dielectric material to obtain a high sensitivity,but also basically maintains the excellent mechanical properties of the polymer matrix.The dielectric constants of the composite films increase from 5.68 to 13.13 at 10 kHz with the increase of BT NPs content from 0 to 15 vol.%,which results in a high capacitance of 236.16 pF for 15 vol.%BT/p(BA-GMA)sensor.Combining the high permittivity and the large deformability(a maximal deformation of 87.2%),the 15 vol.%BT/p(BA-GMA)sensor has high sensitivity and shows high linearity and stable output even if under dynamic measurement.The dual-mode sensor that utilizes the orthogonality of capacitance-resistance is designed,which shows excellent performance in monitoring human body movements and noncontact measurement.The results present that the BT/p(BA-GMA)-based sensor has high stability and reliability not exceed 65C,which can meet the application requirements in dynamic monitoring.展开更多
Stretchable strain sensors play a key role in motion detection and human-machine interface functionality,and deformation control.However,their sensitivity is often limited by the Poisson effect of elastic substrates.I...Stretchable strain sensors play a key role in motion detection and human-machine interface functionality,and deformation control.However,their sensitivity is often limited by the Poisson effect of elastic substrates.In this study,a stretchable strain sensor based on a continuous-fiber-reinforced auxetic structure was proposed and fabricated using a direct ink writing(DIW)3D printing process.The application of multi-material DIW greatly simplifies the fabrication process of a sensor with an auxetic structure(auxetic sensor).The auxiliary auxetic struc-ture was innovatively printed using a continuous-fiber-reinforced polydimethylsiloxane composite(Fiber-PDMS)to balance the rigidity and flexibility of the composite.The increase in stiffness enhances the negative Poisson’s ratio effect of the auxetic structure,which can support the carbon nanotube-polydimethylsiloxane composite(CNT-PDMS)stretchable sensor to produce a significant lateral expansion when stretched.It is shown that the structural Poisson’s ratio of the sensor decreased from 0.42 to−0.33 at 20%tensile strain,and the bidirectional tensile strain increases the sensor sensitivity by 2.52 times(gage factor to 18.23).The Fiber-PDMS composite maintains the excellent flexibility of the matrix material.The auxetic sensor exhibited no structural damage af-ter 150 cycles of tension and the signal output exhibited high stability.In addition,this study demonstrates the significant potential of auxetic sensors in the field of deformation control.展开更多
Carbon nanotubes have potential applications in flexible and stretchable devices due to their remarkable electromechanical properties.Flexible and stretchable strain sensors of multi-walled carbon nanotubes（MWCNTs）w...Carbon nanotubes have potential applications in flexible and stretchable devices due to their remarkable electromechanical properties.Flexible and stretchable strain sensors of multi-walled carbon nanotubes（MWCNTs）with aligned or random structures were fabricated on poly-dimethylsiloxane（PDMS） substrate with different techniques.It was observed that the spraycoatedtechniquebased strain sensor fabricated on PDMS substrate showed higher sensitivity higher stretchability,better linearity and excellent longer time stability than the sensor fabricated with other methods presented in this work.The scanning electron microscopy images indicated the spray coating technique can produce a better uniform and compact CNT network,which is the important role affecting the performance of CNT-based flexible strain sensors.展开更多
With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human bod...With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human body and high-fidelity collec-tion of biological information remains a significant challenge.Here,a nanoconfinement self-assembly strategy is developed to prepare elastic phenylalanine dipeptide(FF)crystal fibers,in which FF crystals form a unique Mortise-Tenon structure with oriented styrene-block-butadiene-block-styrene molecular beams and thereby obtain elasticity(≈1200%),flexibility(Young’s modulus:0.409±0.031 MPa),piezoelectricity(macroscopic d_(33):10.025±0.33 pC N^(-1)),breathability,and physical stability.Furthermore,elastic FF crystal fibers are used to develop a flexible human physiological movement sensing system by integrating Ga–In alloy coating and wireless electronic transmission components.The system can undergo conformal deformation with human skin and achieve high-fidelity capture of biological information originating from human body motions to prevent diseases(such as Parkinson’s disease).In addition,this system also displays superior sensitivity and accu-racy in detecting subtle pressure changes in vivo during heartbeats,respiration,and diaphragm movement.Therefore,elastic FF crystal fibers hold great potential for developing new flexible electromechanical sensors that are capable of conformal deformation with the human body,enabling precision medical diagnosis and efficient energy harvesting.展开更多
Ammonia(NH3)is the second-most-produced chemical worldwide and has numerous industrial applications.However,such applications pose significant risks,as evidenced by human casualties caused by NH_(3) leaks or poisoning...Ammonia(NH3)is the second-most-produced chemical worldwide and has numerous industrial applications.However,such applications pose significant risks,as evidenced by human casualties caused by NH_(3) leaks or poisoning in confined environments.This highlights the critical need for highly portable and intuitive wearable NH_(3) sensors.The chemiresistive sensors are widely employed in wearable devices due to their simple structure,high sensitivity,and short response times,but are prone to malfunctioning and inaccurate gas detection because of the corrosion or failure of the sensing material under the influence of humidity,high temperatures,and interfering gas species.Addressing these limitations,a gas-sensing platform with a polymer-based nanofiber structure has been developed,providing flexibility and facilitating efficient transport of NH_(3) between the colorimetric(bromocresol-green-based)and chemiresistive(poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)-based)sensing layers.This dual-mode design enables reliable NH_(3) detection.The NH_(3)-sensing performance of each individual layer is comparable to that of the dual-mode gas-sensing platform,which operates effectively even when attached to human skin and in humid environments.Therefore,this study establishes a robust,selective,and reproducible NH3 sensor for diverse applications and introduces an innovative sensor engineering paradigm.展开更多
Flexible sensors have attracted wide attention like never before in the fast-growing flexible electronics era,because they are easily adaptable to curved or soft surfaces based on their inherent flexibility and simult...Flexible sensors have attracted wide attention like never before in the fast-growing flexible electronics era,because they are easily adaptable to curved or soft surfaces based on their inherent flexibility and simultaneously detect multiple external stimuli.In the field of intelligent driving,they utilize novel conductive materials,including conductive polymers,carbon-based nanomaterials,and liquid metals,to construct multifunctional flexible sensor networks,thereby accomplishing seamless integration with curved vehicle surfaces and comprehensive status monitoring.The advantages are that achieving dynamic deformation adaptability through flexible materials and manufacturing,enhancing system redundancy/robustness/real-time performance through a sensor network deployment,and improving perception accuracy through multimodal fusion.Therefore,flexible sensors exhibit great potential in intelligent cockpit interaction,chassis obstacle detection,and vehicle health diagnostics.However,its large-scale commercialization still faces challenges in automotive-grade integration,weather resistance,data security,and power supply.Furthermore,flexible sensors are expected to integrate with AI models,lightweight architectures,and self-healing smart materials in the future,thereby advancing autonomous driving development,facilitating vehicle-road-cloud coordination,and revolutionizing mobility paradigms.展开更多
Stretchable strain sensor detects a wide range of strain variation and is therefore a key component in various applications.Unlike traditional ones made of elastomers doped with conductive components or fabricated wit...Stretchable strain sensor detects a wide range of strain variation and is therefore a key component in various applications.Unlike traditional ones made of elastomers doped with conductive components or fabricated with liquid conductors,ionically conductive hydrogel-based strain sensors remain conductive under large deformations and are biocompatible.However,dehydration is a challenging issue for the latter.Researchers have developed hydrogel-elastomer-based strain sensors where an elastomer matrix encapsulates a hydrogel circuit to prevent its dehydration.However,the reported multistep approaches are generally time-consuming.Our group recently reported a multimaterial 3D printing approach that enables fast fabrication of such sensors,yet requires a self-built digital-light-processing-based multimaterial 3D printer.Here,we report a simple projection lithography method to fabricate hydrogel-elastomer-based stretchable strain sensors within 5 minutes.This method only requires a UV projector/lamp with photomasks;the chemicals are commercially available;the protocols for preparing the polymer precursors are friendly to users without chemistry background.Moreover,the manufacturing flexibility allows users to readily pattern the sensor circuit and attach the sensor to a 3D printed soft pneumatic actuator to enable strain sensing on the latter.The proposed approach paves a simple and versatile way to fabricate hydrogel-elastomer-based stretchable strain sensors and flexible electronic devices.展开更多
基金Supported by National Natural Science Foundation of China(Grant No.51075327)Open Project of State Key Laboratory for Strength and Vibration of Mechanical Structures of China(Grant No.SV2014-KF-08)Shaanxi Provincial Natural Science Foundation of China(Grant No.2014JM2-5082)
文摘The stretchable sensor wrapped around a foldable airfoil or embedded inside of it has great potential for use in the monitoring of the structural status of the foldable airfoil.The design methodology is important to the development of the stretchable sensor for status monitoring on the foldable airfoil.According to the requirement of mechanical flexibility of the sensor,the combined use of a layered flexible structural formation and a strain isolation layer is implemented.An analytical higher-order model is proposed to predict the stresses of the strain-isolation layer based on the shear-lag model for the safe design of the flexible and stretchable sensors.The normal stress and shear stress equations in the constructed structure of the sensors are obtained by the proposed model.The stress distribution in the structure is investigated when bending load is applied to the structures.The numerical results show that the proposed model can predict the variation of normal stress and shear stress along the thickness of the strain-isolation(polydimethylsiloxane)layer accurately.The results by the proposed model are in good agreement with the finite element method,in which the normal stress is variable while the shear stress is invariable along the thickness direction of strain-isolation layer.The high-order model is proposed to predict the stresses of the layered structure of the flexible and stretchable sensor for monitoring the status of the foldable airfoil.
基金supported by the National Key Research and Development Program of China(2022YFA1104802)the National Natural Science Foundation of China(22122408,21721005,22090051)。
文摘Vascular endothelium can perceive fluid shear stress(FSS)and cyclic circumferential stretch(CCS)caused by the pulsatile blood flow,and translate the hemodynamics into biochemical signals to regulate vascular pathophysiology.However,existing methods provide little information about the real-time biochemical responses of endothelium when exposed to dynamic FSS and CCS.Herein,a vasculature-on-a-chip integrated with stretchable sensing is engineered for recapitulating the hemodynamic milieus and in-situ monitoring biochemical responses of endothelial monolayer.The integrated device is developed by sandwiching a robust stretchable electrode between an upper fluidic channel and a lower pneumatic channel.The fluidic and pneumatic channels enable the simultaneous recapitulation of both FSS and CCS,and the integrated sensor exhibits excellent cell-adhesive capacity and electrochemical sensing stability even after long-term hemodynamic exposure.These allow real-time monitoring of hemodynamic form-and duration-dependent endothelium responses,and further efficacy investigation about a recommended drug for COVID-19,demonstrating the great potential in vascular disease and drug screening.
基金National Natural Science Foundation of China,Grant/Award Number:62001322。
文摘Continuous and quantitative monitoring of knee joint function has clinical value in rehabilitation assessment and the timing of return to play for anterior cruciate ligament injury patients.However,the existing approaches,including clinical examination,arthrometry and inertial solutions,can only be used for qualitative,off-line and low-quality evaluations,respectively.Burgeoning Kirigami stretchable sensors could be a disruptive candidate solution,but they usually suffer from structural buckling issues when used for large strain applications,such as knee joint motion capture where the buckling degrades sensor reliability and repeatability.Here,we propose a buckling-resistant stretchable and wearable sensor for knee joint motion capture.It enables continuous and precise motion signal capture of the knee joint and provides high wearing comfort and reliability.Clinical tests were conducted on 30 patients in the field,tracking data provided by the sensor from their initial hospitalization to later surgery.And the full rehabilitation of one subject was recorded and analyzed.The test results show that our sensor can dynamically assess knee function in real time and recommend the best timing for return to play,which paves the way for personalized and telerehabilitation.
基金support from the National Natural Science Foundation of China(61801525)the Guangdong Basic and Applied Basic Research Foundation(2020A1515010693)+1 种基金the Guangdong Natural Science Funds Grant(2018A030313400),the Science and Technology Program of Guangzhou(201904010456)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(2021qntd09).
文摘With the advent of the 5G era and the rise of the Internet of Things,various sensors have received unprecedented attention,especially wearable and stretchable sensors in the healthcare field.Here,a stretchable,self-healable,self-adhesive,and room-temperature oxygen sensor with excellent repeatability,a full concentration detection range(0-100%),low theoretical limit of detection(5.7 ppm),high sensitivity(0.2%/ppm),good linearity,excellent temperature,and humidity tolerances is fabricated by using polyacrylamide-chitosan(PAM-CS)double network(DN)organohydrogel as a novel transducing material.The PAM-CS DN organohydrogel is transformed from the PAM-CS composite hydrogel using a facile soaking and solvent replacement strategy.Compared with the pristine hydrogel,the DN organohydrogel displays greatly enhanced mechanical strength,moisture retention,freezing resistance,and sensitivity to oxygen.Notably,applying the tensile strain improves both the sensitivity and response speed of the organohydrogel-based oxygen sensor.Furthermore,the response to the same concentration of oxygen before and after self-healing is basically the same.Importantly,we propose an electrochemical reaction mechanism to explain the positive current shift of the oxygen sensor and corroborate this sensing mechanism through rationally designed experiments.The organohydrogel oxygen sensor is used to monitor human respiration in real-time,verifying the feasibility of its practical application.This work provides ideas for fabricating more stretchable,self-healable,self-adhesive,and high-performance gas sensors using ion-conducting organohydrogels.
文摘The Design and manufacturing of a noble piezoresistive pressure sensor(PS) for subtle pressures(<1 kPa) were presented. Meanwhile, in the studies conducted in the field of pressure sensors, the measurement of subtle pressures has received less attention. The limitations in the inherent gauge factor in silicon, have led to the development of polymer and composite resistive sensitive elements. However,in the development of resistance sensing elements, the structure of composite elements with reinforcement core has not been used. The proposed PS had a composite sandwich structure consisting of a nanocomposite graphene layer covered by layers of PDMS at the bottom and on the top coupled with a polyimide(PI) core. Various tests were performed to analyze the PS. The primary design target was improved sensitivity, with a finite-element method(FEM) utilized to simulate the stress profile over piezoresistive elements and membrane deflection at various pressures. The PS manufacturing process is based on Laser-engraved graphene(LEG) technology and PDMS casting. Experimental data indicated that the manufactured PS exhibits a sensitivity of 67.28 mV/kPa for a pressure range of 30-300 Pa in ambient temperature.
基金supported by the National Research Founda-tion of Korea(NRF)grant funded by the Ministry of Science and ICT(Nos.2022R1A2B5B02002413 and 2022R1A4A1031182)the Korea Planning&Evaluation Institute of Industrial Technology(KEIT)funded by the Ministry of Trade,Industry and Energy(MOTIE)of Korea(No.20020899,Development of high-performance heat dissipation sheets using graphitization of polymer composites with vertical graphene)In addition,this study was supported by the Korea Institute of Indus-trial Technology(kitech JA-20-0001 and kitech EH-23-0001).
文摘Stretchable strain sensors have great potential for diverse applications including human motion detection,soft robotics,and health monitoring.However,their practical implementation requires improved repeatability and stability along with high sensing performances.Here,we utilized spiky vertical graphene(VG)sheets decorated on carbon nanofibers(VG@CNFs)to establish reliable conductive networks for resistive strain sensing.Three-dimensional(3D)VG@CNFs combined with reduced graphene oxide(rGO)sheets were simply coated on stretchable spandex fibers by ultrasonication.Because of the spiky geometry of the VG sheets,VG@CNF and rGO exhibited enhanced interactions,which was confirmed by mode I fracture tests.Due to the robust conductive networks formed by the VG@CNF and rGO hybrid,the fiber strain sensor exhibited a significantly improved strain range of up to 522%(with a high gauge factor of 1358)and stable resistance changes with minimal variation even after 5000 stretching–releasing cycles under a strain of 50%.In addition,the textile strain sensor based on the VG@CNF/rGO hybrid showed even improved repeatability for various strain levels of 10%to 200%,enabling its implementation on leggings for monitoring of squat posture.This study demonstrates the high potential of the 3D VG@CNF for high-performance and reliable stretchable strain sensors.
基金supported by National Natural Science Foundation of China (51575016)the Beijing Oversea High-Level Talent Project+1 种基金strategic research Grant (KZ20141000500, B-type) of Beijing Natural Science Foundation P.R. Chinathe support by the China Scholarship Council (20160654015) for his research stay at the Institute of Physical and Chemical Research,Wako, Japan
文摘Stretchable electronic sensing devices are defining the path toward wearable electronics. High-performance flexible strain sensors attached on clothing or human skin are required for potential applications in the entertainment,health monitoring, and medical care sectors. In this work,conducting copper electrodes were fabricated onpolydimethylsiloxane as sensitive stretchable microsensors by integrating laser direct writing and transfer printing approaches. The copper electrode was reduced from copper salt using laser writing rather than the general approach of printing with pre-synthesized copper or copper oxide nanoparticles. An electrical resistivity of 96 l X cm was achieved on 40-lm-thick Cu electrodes on flexible substrates. The motion sensing functionality successfully demonstrated a high sensitivity and mechanical robustness.This in situ fabrication method leads to a path toward electronic devices on flexible substrates.
基金Jin Wu acknowledges financial support from the National Natural Science Foundation of China(No.61801525)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010693)+1 种基金the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.22lgqb17)the Independent Fund of the State Key Laboratory of Optoelectronic Materials and Technologies(Sun Yat-sen University)under grant No.OEMT-2022-ZRC-05.
文摘Breathing is an inherent human activity;however,the composition of the air we inhale and gas exhale remains unknown to us.To address this,wearable vapor sensors can help people monitor air composition in real time to avoid underlying risks,and for the early detection and treatment of diseases for home healthcare.Hydrogels with three-dimensional polymer networks and large amounts of water molecules are naturally flexible and stretchable.Functionalized hydrogels are intrinsically conductive,self-healing,self-adhesive,biocompatible,and room-temperature sensitive.Compared with traditional rigid vapor sensors,hydrogel-based gas and humidity sensors can directly fit human skin or clothing,and are more suitable for real-time monitoring of personal health and safety.In this review,current studies on hydrogel-based vapor sensors are investigated.The required properties and optimization methods of wearable hydrogel-based sensors are introduced.Subsequently,existing reports on the response mechanisms of hydrogel-based gas and humidity sensors are summarized.Related works on hydrogel-based vapor sensors for their application in personal health and safety monitoring are presented.Moreover,the potential of hydrogels in the field of vapor sensing is elucidated.Finally,the current research status,challenges,and future trends of hydrogel gas/humidity sensing are discussed.
基金the National Natural Science Foundation of China(No.62001322)the Tianjin Municipal Science and Technology Project(No.20JCQNJC011200)+1 种基金the National Key Research and Development Program of China(No.2020YFB2008801)the Nanchang Institute for Microtechnology of Tianjin University.
文摘Today,the vast majority of microelectromechanical system(MEMS)sensors are mechanically rigid and therefore suffer from disadvantages when used in intimately wearable or bio-integrated applications.By applying new engineering strategies,mechanically bendable and stretchable MEMS devices have been successfully demonstrated.This article reviews recent progress in this area,focusing on high-performance flexible devices based on inorganic thin films.We start with the common design and fabrication strategies for flexibility and stretchability,summarize the recent application-oriented flexible devices,and conclude with criteria and opportunities for the future development of flexible MEMS sensors.
基金J.W.acknowledges financial supports from the National Natural Science Foundation of China(61801525)the Guangdong Basic and Applied Basic Research Foundation(2020A1515010693)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(22lgqb17).
文摘Respiratory monitoring plays a pivotal role in health assessment and provides an important application prospect for flexible humidity sensors.However,traditional humidity sensors suffer from a trade-off between deformability,sensitivity,and transparency,and thus the development of high-performance,stretchable,and low-cost humidity sensors is urgently needed as wearable electronics.Here,ultrasensitive,highly deformable,and transparent humidity sensors are fabricated based on cost-effective polyacrylamide-based double network hydrogels.Concomitantly,a general method for preparing hydrogel films with controllable thickness is proposed to boost the sensitivity of hydrogel-based sensors due to the extensively increased specific surface area,which can be applied to different polymer networks and facilitate the development of flexible integrated electronics.In addition,sustainable tapioca rich in hydrophilic polar groups is introduced for the first time as a second cross-linked network,exhibiting excellent water adsorption capacity.Through the synergistic optimization of structure and composition,the obtained hydrogel film exhibits an ultrahigh sensitivity of 13,462.1%/%RH,which is unprecedented.Moreover,the hydrogel film-based sensor exhibits excellent repeatability and the ability to work normally under stretching with even enhanced sensitivity.As a proof of concept,we integrate the stretchable sensor with a specially designed wireless circuit and mask to fabricate a wireless respiratory interruption detection system with Bluetooth transmission,enabling real-time monitoring of human health status.This work provides a general strategy to construct high-performance,stretchable,and miniaturized hydrogel-based sensors as next-generation wearable devices for real-time monitoring of various physiological signals.
基金supported by the Distinguished Young Scholars[2022JDJQ0028]Research Startup Fund by Sichuan University[YJ202218].
文摘With the fast-evolving landscape of flexible and wearable electronics,functional fibers for withstanding high strains in smart wearables,soft robotics,and health monitoring systems are under increasing demands.We report ultra-stretchable and conductive fibers with a thermal drawing process,controlled and engineered for precise motion sensing.This approach enables uniform fibers with microcavities,facilitating scalable production of elastic and functional fibers through a simple fabrication process.Integrating liquid metal(Eutectic Gallium-Indium-Tin alloys)into the elastic fiber yielded a device with a high gauge factor(GF)of 0.91,remarkable linearity(R^(2)=0.999),rapid response time(100 ms),and low hysteresis(<3%)up to 1000% strain.The SFCSS could be readily integrated into textiles,such as gloves and clothing,enabling detection of a wide range of human motions,including static sensing of finger motion,knee posture and dynamic activities of standing,sitting,squatting,walking,and running.Additionally,the SFCSS demonstrated effectiveness in measuring boundary-lengths of irregular objects,supporting applications in soft robotics.The ultra-stretchable capacitive strain sensor developed in this work provides a new approach to enable wearable electronics and smart textiles for the upcoming era of interactive human-machine interfaces and digital healthcare.
基金This research was financially supported by the National Natural Science Foundation of China(Nos.51673214 and 61804185)the National Key Research and Development Program of China(No.2017YFA0206600)+1 种基金the Natural Science Foundation of Hunan Province(No.2019JJ50804)the Free Exploration and Innovation Project of Central South University(No.2019zzts427).
文摘Flexible strain sensors exhibit outstanding advantages in terms of sensitivity and stability by detecting changes in physical signals.It can be easily attached to human skin and clothed to achieve monitoring of human motion and health.However,general sensing material shows low stretchability and cannot respond to signals under large deformation.In this work,a highly stretchable polymer composite was developed by adding small amount(0.17 wt.%)of silver nanowires(AgNWs)in stretchable conductive polymer materials.The conductivity of polymer/AgNWs composite is 1.3 S/m with the stretchability up to 500%.The stretchable strain sensor based on the polymer/AgNWs composite can respond to strain signals in real time,even for 1%strain response,and shows excellent stability over 1,000 loading/unloading cycles.Moreover,the strain sensor can be attached to human skin and clothed to monitor joints,throat and pulse of the human body.The human body electrocardiogram(ECG)signal was detected successfully with the polymer/AgNWs electrode,which is comparable to the signal obtained by the commercial electrode.Overall,the sensors enable monitoring of human movement and health.These advantages make it a potential application in wearable devices and electronic skin.
基金financial support from the National Natural Science Foundation of China (No. 61801525)the Guangdong Basic and Applied Basic Research Foundation (Nos. 2020A1515010693, 2021A1515110269)+1 种基金the Fundamental Research Funds for the Central Universities, Sun Yatsen University (No. 22lgqb17)the Independent Fund of the State Key Laboratory of Optoelectronic Materials and Technologies (Sun Yat-sen University) under grant No. OEMT-2022-ZRC-05。
文摘Growing health awareness triggers the public's concern about health problems. People want a timely and comprehensive picture of their condition without frequent trips to the hospital for costly and cumbersome general check-ups. The wearable technique provides a continuous measurement method for health monitoring by tracking a person's physiological data and analyzing it locally or remotely.During the health monitoring process,different kinds of sensors convert physiological signals into electrical or optical signals that can be recorded and transmitted, consequently playing a crucial role in wearable techniques. Wearable application scenarios usually require sensors to possess excellent flexibility and stretchability. Thus, designing flexible and stretchable sensors with reliable performance is the key to wearable technology. Smart composite hydrogels, which have tunable electrical properties, mechanical properties, biocompatibility, and multi-stimulus sensitivity, are one of the best sensitive materials for wearable health monitoring. This review summarizes the common synthetic and performance optimization strategies of smart composite hydrogels and focuses on the current application of smart composite hydrogels in the field of wearable health monitoring.
基金supported by the National Natural Science Foundation of China(Grant Nos.51972032,51937007,and 51921005)Science and Technology Program of the State Grid Corporation of China(5500-201999527A-0-0-00)+1 种基金Science and Technology Program of Shenzhen Science and Technology Innovation Commission(Grant No.JCYJ20180306173235924)BUPT Excellent Ph.D.Students Foundation(CX2021128).
文摘Large deformability and high sensitivity is difficult to be realized simultaneously in flexible sensors.Herein,taking advantage of the high permittivity and highly active surfaces of the ultrasmall barium titanate nanoparticles(BT NPs)and the high stretchability of the p(BA-GMA)elastomer matrix,we propose a high-performance soft stretchable sensor.The addition of the ultrasmall BT NPs can not only increase the permittivity and capacitance of polyacrylate-matrix composite dielectric material to obtain a high sensitivity,but also basically maintains the excellent mechanical properties of the polymer matrix.The dielectric constants of the composite films increase from 5.68 to 13.13 at 10 kHz with the increase of BT NPs content from 0 to 15 vol.%,which results in a high capacitance of 236.16 pF for 15 vol.%BT/p(BA-GMA)sensor.Combining the high permittivity and the large deformability(a maximal deformation of 87.2%),the 15 vol.%BT/p(BA-GMA)sensor has high sensitivity and shows high linearity and stable output even if under dynamic measurement.The dual-mode sensor that utilizes the orthogonality of capacitance-resistance is designed,which shows excellent performance in monitoring human body movements and noncontact measurement.The results present that the BT/p(BA-GMA)-based sensor has high stability and reliability not exceed 65C,which can meet the application requirements in dynamic monitoring.
基金This work was supported by National Natural Science Foundation of China(Grant No.52075422)Rapid Manufacturing Engineering Technology Research Center of Shaanxi Province of China(Grant No.2017HBGC-06)Youth Innovation Team of Shaanxi Universities,and K.C.Wong Education Foundation.
文摘Stretchable strain sensors play a key role in motion detection and human-machine interface functionality,and deformation control.However,their sensitivity is often limited by the Poisson effect of elastic substrates.In this study,a stretchable strain sensor based on a continuous-fiber-reinforced auxetic structure was proposed and fabricated using a direct ink writing(DIW)3D printing process.The application of multi-material DIW greatly simplifies the fabrication process of a sensor with an auxetic structure(auxetic sensor).The auxiliary auxetic struc-ture was innovatively printed using a continuous-fiber-reinforced polydimethylsiloxane composite(Fiber-PDMS)to balance the rigidity and flexibility of the composite.The increase in stiffness enhances the negative Poisson’s ratio effect of the auxetic structure,which can support the carbon nanotube-polydimethylsiloxane composite(CNT-PDMS)stretchable sensor to produce a significant lateral expansion when stretched.It is shown that the structural Poisson’s ratio of the sensor decreased from 0.42 to−0.33 at 20%tensile strain,and the bidirectional tensile strain increases the sensor sensitivity by 2.52 times(gage factor to 18.23).The Fiber-PDMS composite maintains the excellent flexibility of the matrix material.The auxetic sensor exhibited no structural damage af-ter 150 cycles of tension and the signal output exhibited high stability.In addition,this study demonstrates the significant potential of auxetic sensors in the field of deformation control.
基金Project supported by the National Basic Research Program of China(No.2015CB351905)the National Natural Science Foundation of China(No.61306015)+1 种基金the Technology Innovative Research Team of Sichuan Province of China(No.2015TD0005)"111"Project(No.B13042)
文摘Carbon nanotubes have potential applications in flexible and stretchable devices due to their remarkable electromechanical properties.Flexible and stretchable strain sensors of multi-walled carbon nanotubes（MWCNTs）with aligned or random structures were fabricated on poly-dimethylsiloxane（PDMS） substrate with different techniques.It was observed that the spraycoatedtechniquebased strain sensor fabricated on PDMS substrate showed higher sensitivity higher stretchability,better linearity and excellent longer time stability than the sensor fabricated with other methods presented in this work.The scanning electron microscopy images indicated the spray coating technique can produce a better uniform and compact CNT network,which is the important role affecting the performance of CNT-based flexible strain sensors.
基金support from the National Natural Science Foundation of China(82472159,82302406,52303186)China Postdoctoral Science Foundation(2024T171167,2023M731696,2022TQ0158,2022M721616)+1 种基金Jiangsu Funding Program for Excellent Postdoctoral Talent(2023ZB539,2022ZB250)the Fundamental Research Funds for the Central Universities(30923010307,30920041105).
文摘With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human body and high-fidelity collec-tion of biological information remains a significant challenge.Here,a nanoconfinement self-assembly strategy is developed to prepare elastic phenylalanine dipeptide(FF)crystal fibers,in which FF crystals form a unique Mortise-Tenon structure with oriented styrene-block-butadiene-block-styrene molecular beams and thereby obtain elasticity(≈1200%),flexibility(Young’s modulus:0.409±0.031 MPa),piezoelectricity(macroscopic d_(33):10.025±0.33 pC N^(-1)),breathability,and physical stability.Furthermore,elastic FF crystal fibers are used to develop a flexible human physiological movement sensing system by integrating Ga–In alloy coating and wireless electronic transmission components.The system can undergo conformal deformation with human skin and achieve high-fidelity capture of biological information originating from human body motions to prevent diseases(such as Parkinson’s disease).In addition,this system also displays superior sensitivity and accu-racy in detecting subtle pressure changes in vivo during heartbeats,respiration,and diaphragm movement.Therefore,elastic FF crystal fibers hold great potential for developing new flexible electromechanical sensors that are capable of conformal deformation with the human body,enabling precision medical diagnosis and efficient energy harvesting.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(RS-2024-00412335)supported by the Korea Institute of Marine Science and Technology Promotion(KIMST),funded by the Ministry of Oceans and Fisheries(RS-2022-KS221606).
文摘Ammonia(NH3)is the second-most-produced chemical worldwide and has numerous industrial applications.However,such applications pose significant risks,as evidenced by human casualties caused by NH_(3) leaks or poisoning in confined environments.This highlights the critical need for highly portable and intuitive wearable NH_(3) sensors.The chemiresistive sensors are widely employed in wearable devices due to their simple structure,high sensitivity,and short response times,but are prone to malfunctioning and inaccurate gas detection because of the corrosion or failure of the sensing material under the influence of humidity,high temperatures,and interfering gas species.Addressing these limitations,a gas-sensing platform with a polymer-based nanofiber structure has been developed,providing flexibility and facilitating efficient transport of NH_(3) between the colorimetric(bromocresol-green-based)and chemiresistive(poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate)-based)sensing layers.This dual-mode design enables reliable NH_(3) detection.The NH_(3)-sensing performance of each individual layer is comparable to that of the dual-mode gas-sensing platform,which operates effectively even when attached to human skin and in humid environments.Therefore,this study establishes a robust,selective,and reproducible NH3 sensor for diverse applications and introduces an innovative sensor engineering paradigm.
基金the National Natural Science Foundation of China(No.52525502,No.52205593,No.52427809)the Xidian University Specially Funded Project for Interdisciplinary Exploration(No.TZJH2024061)+1 种基金Proof of Concept Foundation of Xidian University Hangzhou Institute of Technology(Grant No.GNYZ2024QC008)the Special Project of Central Government for Local Science and Technology Development of Hubei Province(No.2024AFE002).
文摘Flexible sensors have attracted wide attention like never before in the fast-growing flexible electronics era,because they are easily adaptable to curved or soft surfaces based on their inherent flexibility and simultaneously detect multiple external stimuli.In the field of intelligent driving,they utilize novel conductive materials,including conductive polymers,carbon-based nanomaterials,and liquid metals,to construct multifunctional flexible sensor networks,thereby accomplishing seamless integration with curved vehicle surfaces and comprehensive status monitoring.The advantages are that achieving dynamic deformation adaptability through flexible materials and manufacturing,enhancing system redundancy/robustness/real-time performance through a sensor network deployment,and improving perception accuracy through multimodal fusion.Therefore,flexible sensors exhibit great potential in intelligent cockpit interaction,chassis obstacle detection,and vehicle health diagnostics.However,its large-scale commercialization still faces challenges in automotive-grade integration,weather resistance,data security,and power supply.Furthermore,flexible sensors are expected to integrate with AI models,lightweight architectures,and self-healing smart materials in the future,thereby advancing autonomous driving development,facilitating vehicle-road-cloud coordination,and revolutionizing mobility paradigms.
基金This work was supported by the National Key Research and Development Program of China[NO.2020YFB1312900]the Science,Technology and Innovation Commission of Shenzhen Municipality[ZDSYS20200811143601004]+1 种基金the Agency for Science,Technology and Research(A*STAR,Singapore)AME Programmatic Funding Scheme[A18A1b0045]the SUTD Digital Manufacturing and Design Center(DManD).
文摘Stretchable strain sensor detects a wide range of strain variation and is therefore a key component in various applications.Unlike traditional ones made of elastomers doped with conductive components or fabricated with liquid conductors,ionically conductive hydrogel-based strain sensors remain conductive under large deformations and are biocompatible.However,dehydration is a challenging issue for the latter.Researchers have developed hydrogel-elastomer-based strain sensors where an elastomer matrix encapsulates a hydrogel circuit to prevent its dehydration.However,the reported multistep approaches are generally time-consuming.Our group recently reported a multimaterial 3D printing approach that enables fast fabrication of such sensors,yet requires a self-built digital-light-processing-based multimaterial 3D printer.Here,we report a simple projection lithography method to fabricate hydrogel-elastomer-based stretchable strain sensors within 5 minutes.This method only requires a UV projector/lamp with photomasks;the chemicals are commercially available;the protocols for preparing the polymer precursors are friendly to users without chemistry background.Moreover,the manufacturing flexibility allows users to readily pattern the sensor circuit and attach the sensor to a 3D printed soft pneumatic actuator to enable strain sensing on the latter.The proposed approach paves a simple and versatile way to fabricate hydrogel-elastomer-based stretchable strain sensors and flexible electronic devices.
