Temperature stability is essential for the precision of flexible sensors.However,constrained by the composite principle of heterogeneous materials,the existing self-compensating methods encounter substantial challenge...Temperature stability is essential for the precision of flexible sensors.However,constrained by the composite principle of heterogeneous materials,the existing self-compensating methods encounter substantial challenges.To tackle this,high-entropy alloy nanofibers were utilized to construct a flexible strain sensor with inherent temperature stability.This approach leverages the electrohydrodynamic direct writing;a precursor conductive network was established through the electrospinning of a high-entropy alloy acetate and polyvinylidene difluoride solution blend.Subsequently,annealing treatment facilitated metallization,resulting in the synergistic preservation of polymer stretchability and the low temperature coefficient of resistance properties of high-entropy alloys inside the nanofibers.The test results demonstrate that the high-entropy alloys flexible strain sensor exhibits a remarkably low temperature coefficient of resistance(45.59 ppm K^(-1))across the range of-10 to 70℃,a sensitivity coefficient GF of 1.12 with a 50%strain range,and a response time of 310 ms.After 6000 stretching cycles,no baseline drift or failure occurred,indicating excellent cyclic stability.Furthermore,the outstanding temperature stability of the sensor was validated through wearable application and robotic hands strain sensing conducted under varied environment temperatures.This work provides a viable design pathway for developing flexible sensors with an inherently low temperature coefficient of resistance.展开更多
This study presents a breakthrough in flexible strain sensor technology with the development of an ultrahigh sensitivity and wide-range sensor,addressing the critical challenge of reconciling sensitivity with measurem...This study presents a breakthrough in flexible strain sensor technology with the development of an ultrahigh sensitivity and wide-range sensor,addressing the critical challenge of reconciling sensitivity with measurement range.Inspired by the structure of bamboo slips,we introduce a novel approach that utilises liquid metal to modulate the electrical pathways within a cracked platinum fabric electrode.The resulting sensor demonstrates a gauge factor greater than 108 and a strain measurement capability exceeding 100%.The integration of patterned liquid metal enables customisable tuning of the sensor’s response,while the porous fabric structure ensures superior comfort and air permeability for the wearer.Our design not only optimises the sensor’s performance but also enhances the electrical stability that is essential for practical applications.Through systematic investigation,we reveal the intrinsic mechanisms governing the sensor’s response,offering valuable insights for the design of wearable strain sensors.The sensor’s exceptional performance across a spectrum of applications,from micro-strain to large-strain detection,highlights its potential for a wide range of real-world uses,demonstrating a significant advancement in the field of flexible electronics.展开更多
Liquid leakage of pipeline networks not only results in considerableresource wastage but also leads to environmental pollution and ecological imbalance.In response to this global issue, a bioinspired superhydrophobic ...Liquid leakage of pipeline networks not only results in considerableresource wastage but also leads to environmental pollution and ecological imbalance.In response to this global issue, a bioinspired superhydrophobic thermoplastic polyurethane/carbon nanotubes/graphene nanosheets flexible strain sensor (TCGS) hasbeen developed using a combination of micro-extrusion compression molding andsurface modification for real-time wireless detection of liquid leakage. The TCGSutilizes the synergistic effects of Archimedean spiral crack arrays and micropores,which are inspired by the remarkable sensory capabilities of scorpions. This designachieves a sensitivity of 218.13 at a strain of 2%, which is an increase of 4300%. Additionally, it demonstrates exceptional durability bywithstanding over 5000 usage cycles. The robust superhydrophobicity of the TCGS significantly enhances sensitivity and stability indetecting small-scale liquid leakage, enabling precise monitoring of liquid leakage across a wide range of sizes, velocities, and compositionswhile issuing prompt alerts. This provides critical early warnings for both industrial pipelines and potential liquid leakage scenariosin everyday life. The development and utilization of bioinspired ultrasensitive flexible strain sensors offer an innovative and effectivesolution for the early wireless detection of liquid leakage.展开更多
With the rapid development of“Internet of Things”and human-computer interaction techniques,it is essential and urgent to develop facile and scalable fabrication platforms for stretchable flexible sensor.Herein,we re...With the rapid development of“Internet of Things”and human-computer interaction techniques,it is essential and urgent to develop facile and scalable fabrication platforms for stretchable flexible sensor.Herein,we report a facile strategy of using the green choline chloride-acrylamide deep eutectic solvent(CC-AM DES)to guide the in-situ ring-opening polymerization ofα-lipoic acid(LA),leading to the successful development of a stretchable ionogel material.The as-prepared ionogel from CC-AM DES system exhibits multifunctional merits including the super stretchability(>9000%),100%UV-blocking ability,tunable adhesiveness(29-414 kPa),high ionic conductivity(4.45×10^(-4) S/cm),and ideal anti-freezing(-27℃).In addition,this outstanding ionogel can be readily coated on various material substrates with designable shapes and patterns.Owning to these promising properties and performances,a scalable flexible strain sensor is assembled from the ionogel and exhibits stable resistance variations(R/R_(0))towards multiple external mechanical stimulus.This study provides a green,cost effective,and scalable strategy to fabricate ionogel materials and multifunctional flexible strain sensors,showing a great potential in the fast-emerging highly stretchable wearable/flexible electronics.展开更多
Elastomers with high strength and toughness,excellent self-healing properties,and biocompatibility have broad application prospects in wearable electronics and other fields,but preparing it remains a challenge.In this...Elastomers with high strength and toughness,excellent self-healing properties,and biocompatibility have broad application prospects in wearable electronics and other fields,but preparing it remains a challenge.In this work,we propose a highly adaptable strategy by introducing the small molecule crosslinking agent of triethanolamine(TEA)to the poly(thioctic acid)(PTA)chains and preparing the PAx Ey elastomers using a simple synthesis step.This strategy stabilizes the PTA chains by constructing multiple non-covalent cross-linked dynamic networks,endowing materials with excellent strength and toughness(tensile strength of 288 kPa,toughness of 278.2 kJ/m3),admirable self-healing properties(self-healing efficiency of 121.6%within 7 h at 70℃),and good biocompatibility.The PAx Ey elastomers can also be combined with MWNTs to become flexible strain sensors,which can be used to monitor human joint movements with high sensitivity,repeatable responses,and stability.展开更多
Conductive polymer composites(CPCs)are widely used in the flexible strain sensors due to their simple fabrication process and controllable sensing properties.However,temperature has a significance impact on the strain...Conductive polymer composites(CPCs)are widely used in the flexible strain sensors due to their simple fabrication process and controllable sensing properties.However,temperature has a significance impact on the strain sensing performance of CPCs.In this paper,the strain sensing characteristics of MWCNTs/PDMS composites under temperature loading were systematically studied.It was found that the sensitivity decreased with the increase of temperature and the phenomenon of shoulder peak also decreased.Based on the theory of polymer mechanics,it was found that temperature could affect the conductive network by changing the motion degree of PDMS molecular chain,resulting in the change of sensing characteristics.Finally,a mathematical model of the resistance against loading condition(strain and temperature),associated with the force−electrical equivalent relationship of composites,was established to discuss the experimental results as well as the sensing mechanism.The results presented in this paper was believed helpful for the further application of strain sensors in different temperature conditions.展开更多
Flexible strain sensor has attracted much attention because of its potential application in human motion detection.In this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS...Flexible strain sensor has attracted much attention because of its potential application in human motion detection.In this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS)with room temperature vulcanized silicone rubber(RTVS).In this paper,the formation mechanism of conductive sponge was studied.Based on the combination of carbonized sponge and RTVS,the strain sensing mechanism and piezoresistive properties are discussed.After research and testing,the CS/RTVS flexible strain sensor has excellent fast response speed and stability,and the maximum strain coefficient of the sensor is 136.27.In this study,the self-developed CS/RTVS sensor was used to monitor the movements of the wrist joint,arm elbow joint and fingers in real time.Research experiments show that CS/RTVS flexible strain sensor has good application prospects in the field of human motion monitoring.展开更多
As the most intuitive way of visual signal feedback,color change is often applied by living organisms to transmit signals and resist natural enemies due to its convenient and direct characteristics.Inspired by the str...As the most intuitive way of visual signal feedback,color change is often applied by living organisms to transmit signals and resist natural enemies due to its convenient and direct characteristics.Inspired by the structure color charge of discoloration of chameleons skin,a photonic hydrogel film that can be used for flexible strain detection was developed.Fe_(3)O_(4)@C nanoparticles were used as photonic crystal units,which could self-assemble into one-dimensional chain-like structure in the hydrogel under magnetic field.The structural color of the film will change with the photonic crystal band gap,the film will produce a synergistic color change under mechanical stretching.The resulting flexible film demonstrates bright structural colors,which exhibits a wide strain response up to 120%and achieves a color dynamic change from red(λ=730 nm)to purple(λ=400 nm).In addition,the prepared film exhibits high sensitivity,short response time and good stabilization.The superior performance of flexible strain detection is attributed to the flexible large deformation and good optical properties of the hydrogel film and highly tunable grating structure of the photonic crystal.This work offers a generic approach for the development of visually responsive strain sensors,and provides a wider application prospect in mechanical sensors,stretchable optics,and diagnostics.展开更多
Flexible strain sensors have garnered significant attention for their potential applications in advanced flexible electronics and wearable technologies.However,achieving stable signal transmission at high temperatures...Flexible strain sensors have garnered significant attention for their potential applications in advanced flexible electronics and wearable technologies.However,achieving stable signal transmission at high temperatures remains a major challenge.In this study,we developed a novel polyimide(PI)aerogel composite,reinforced with intrinsically short-cut polyimide nanofibers(PINF)that are surface-coated with silver nanoparticles to enhance both conductivity and mechanical strength.Carbon nanotubes(CNTs)are used as the main filler in synergistic effect with Ag@PINF particles to further improve the conductivity and sensing performance of the composite material.This synergistic design results in a flexible PI aerogel composite material with rapid response time(116 ms),high sensitivity(GF=3.12),and long-term cycling stability(>1000 cycles).Additionally,the sensing materials were tested at high temperatures and after high-temperature aging,demonstrating good flexible sensing performance.Experimental results demonstrate that the composite sensor maintains stable strain-sensing performance across a range of environmental temperatures,showing consistent strain response under the same deformation conditions.This work provides a promising approach for fabricating high-performance,temperature-resistant flexible strain sensors,with broad applications in flexible electronics and wearable technologies.展开更多
Flexible strain sensors with high sensitivity and stability at high temperatures are significantly desirable for their accurate and long-term signal detection in wearable devices,environment monitoring,and aerospace e...Flexible strain sensors with high sensitivity and stability at high temperatures are significantly desirable for their accurate and long-term signal detection in wearable devices,environment monitoring,and aerospace electronics.Despite the considerable efforts in materials development and structural design,it remains a challenge to develop highly sensitive,flexible strain sensors operating at high temperatures due to the trade-off between sensitivity and stability for the representative sensing materials.Herein,we develop a high-temperature flexible sensor using Mo_(x)W_(1-x)S_(2) alloy films.A pulsed laser is introduced to directly synthesize Mo_(x)W_(1-x)S_(2) patterns with controllable compositions and physical parameters,enabling the realization of flexible sensors without photolithography or transfer procedures.The resultant flexible sensors exhibit a high gauge factor of 97.4,a low strain detection of 4.9με,and strong tolerance to a temperature of 500℃.Owing to its superior performance,we develop a wireless acoustic recognition system to distinguish tiny strain signals of tuning forks with a vibration frequency up to 128 Hz under extreme temperature conditions.The laser method for the direct fabrication of Mo_(x)W_(1-x)S_(2) alloy-based flexible sensors holds great potential in the precise detection of strain signals from complex structures at high temperatures.展开更多
Smart agriculture utilizes sensors and software to control agricultural production through mobile or computer platforms,enabling unmanned,automated,and intelligent management.Recently,research and development in plant...Smart agriculture utilizes sensors and software to control agricultural production through mobile or computer platforms,enabling unmanned,automated,and intelligent management.Recently,research and development in plant growth monitoring technologies have garnered significant attention.The challenge lies in achieving long-term monitoring,phased predictions,and plant self-regulation without harming the plants.The present study demonstrates the fabrication of plant-compatible and breathable tensile and bending strain sensors using composite nanofiber membranes(CNMs)composed of Ti_(2)C_(2)T_(x)(MXene),carbon nanotubes(CNTs),and thermoplastic polyurethanes(TPU)through electrospinning and ultrasonic immersion techniques.The MXene and CNTs synergistically form a dual-network conductive structure on the TPU nanofiber membrane,thereby imparting the composite membrane with remarkable tensile sensitivity(5.41,7.39,and 3.39 within the ranges of 0%-20%,20%-50%,and 50%-70%,respectively)as well as exceptional bending sensitivity(1.79,0.89,and 0.46 within the ranges of 0°-30°,30°-90°,and 90°-120°,respectively).The tensile strain sensor,combined with a deep learning Long Short-Term Memory(LSTM)model,establishes a platform for plant growth monitoring and prediction.The bending strain sensor,integrated with a shape memory alloy(SMA)-based soft actuator,forms a plant sensing-actuating system to assist in plant leaf growth.This work leverages MXene/CNTs/TPU CNMs to flexibly prepare strain sensors for specific applications,combining deep learning and soft actuators to achieve plant growth prediction and self-regulation.This research holds significant importance in advancing the development of smart agriculture.展开更多
Carbon fibre(CF)embedded into elastomeric media has been attracting incredible interest as flexible strain sensors in the application of skin electronics owing to their high sensitivity in a very small strain gauge.To...Carbon fibre(CF)embedded into elastomeric media has been attracting incredible interest as flexible strain sensors in the application of skin electronics owing to their high sensitivity in a very small strain gauge.To further improve the sensitivity of CF/PDMS composite strain sensor,the relatively low temperature prepared TiO_(2) nanowire via hydrothermal route was employed herein to functionalize CF.The results showed a significant increase in the sensitivity of the TiO_(2)@CF/PDMS composite strain sensors which was reflected by the calculated gauge factor.As the prepared TiO_(2) nanowire vertically embraced the surroundings of the CF,the introduced TiO_(2) nanowire contributed to a highly porous structure which played a predominant role in improving the sensitivity of strain sensors.Moreover,the significant strain rate dependent behavior of TiO_(2)@CF/PDMS strain sensor was revealed when performing monotonic tests at varied strain rate.Therefore,introducing TiO_(2) nanowire on CF offers a new technique for fabricating flexible strain sensors with improved sensitivity for the application of flexible electronics.展开更多
With the rapid development of wearable electronic skin technology, flexible strain sensors have shown great application prospects in the fields of human motion and physiological signal detection, medical diagnostics, ...With the rapid development of wearable electronic skin technology, flexible strain sensors have shown great application prospects in the fields of human motion and physiological signal detection, medical diagnostics, and human-computer interaction owing to their outstanding sensing performance. This paper reports a strain sensor with synergistic conductive network, consisting of stable carbon nanotube dispersion (CNT) layer and brittle MXene layer by dip-coating and electrostatic self-assembly method, and breathable three-dimensional (3D) flexible substrate of thermoplastic polyurethane (TPU) fibrous membrane prepared through electrospinning technology. The MXene/CNT@PDA-TPU (MC@p-TPU) flexible strain sensor had excellent air permeability, wide operating range (0–450 %), high sensitivity (Gauge Factor, GFmax = 8089.7), ultra-low detection limit (0.05 %), rapid response and recovery times (40 ms/60 ms), and excellent cycle stability and durability (10,000 cycles). Given its superior strain sensing capabilities, this sensor can be applied in physiological signals detection, human motion pattern recognition, and driving exoskeleton robots. In addition, MC@p-TPU fibrous membrane also exhibited excellent photothermal conversion performance and can be used as a wearable photo-heater, which has far-reaching application potential in the photothermal therapy of human joint diseases.展开更多
Flexible strain sensors have been extensively used in human motion detection,medical aids,electronic skins,and other civilian or military fields.Conventional strain sensors made of metal or semiconductor materials suf...Flexible strain sensors have been extensively used in human motion detection,medical aids,electronic skins,and other civilian or military fields.Conventional strain sensors made of metal or semiconductor materials suffer from insufficient stretchability and sensitivity,imposing severe constraints on their utilization in wearable devices.Herein,we design a flexible strain sensor based on biphasic hydrogel via an in-situ polymerization method,which possesses superior electrical response and mechanical performance.External stress could prompt the formation of conductive microchannels within the biphasic hydrogel,which originates from the interaction between the conductive water phase and the insulating oil phase.The device performance could be optimized by carefully regulating the volume ratio of the oil/water phase.Consequently,the flexible strain sensor with oil phase ratio of 80%demonstrates the best sensitivity with gauge factor of 33 upon a compressive strain range of 10%,remarkable electrical stability of 100 cycles,and rapid resistance response of 190 ms.Furthermore,the human motions could be monitored by this flexible strain sensor,thereby highlighting its potential for seamless integration into wearable devices.展开更多
Owing to their good biocompatibility,polysaccharide hydrogels have broad application prospects in the field of flexible strain sensors.However,there are still significant challenges in the preparation of polysaccharid...Owing to their good biocompatibility,polysaccharide hydrogels have broad application prospects in the field of flexible strain sensors.However,there are still significant challenges in the preparation of polysaccharide hydrogels with good mechanical properties.MCA-Li Cl hydrogels were prepared by introducing methacrylated hyaluronic acid(Me HA)into the polymer network in the presence of acrylic acid(AA),acryloyloxyethyltrimethyl ammonium chloride(CATAC),and metal ions.The polymer network not only has a chemically cross-linked network and a tough network structure,but also benefits from a variety of supramolecular interactions,such as hydrogen bonding and coordination covalent bonding,resulting in excellent mechanical properties,with an elongation at break of 1390%,a tensile strength of up to 1200 k Pa,a toughness of 9.4546 MJ/m^(3),and adhesive properties towards various substrates.At the same time,the hydrogel has a high conductivity(5.33 mS/cm)and high strain-sensing sensitivity(Gauge factor=2.55).The flexible strain sensor assembled from the prepared MCA-Li Cl hydrogel can be used to detect human movements,from micro-expressions(smiles,swallowing)to pulse signals and other physiological activities,as well as large-scale joint movements(wrists,elbows,knees,fingers,etc.),realizing the real-time monitoring of full-scale human movements.The prepared hydrogels have potential applications in wearable devices,electronic skin,and strain-sensor components.展开更多
Flexible strain sensor has promising features in successful application of health monitoring, electronic skins and smart robotics, etc.Here, we report an ultrasensitive strain sensor with a novel crack-wrinkle structu...Flexible strain sensor has promising features in successful application of health monitoring, electronic skins and smart robotics, etc.Here, we report an ultrasensitive strain sensor with a novel crack-wrinkle structure(CWS) based on graphite nanoplates(GNPs)/thermoplastic urethane(TPU)/polydimethylsiloxane(PDMS) nanocomposite. The CWS is constructed by pressing and dragging GNP layer on TPU substrate,followed by encapsulating with PDMS as a protective layer. On the basis of the area statistics, the ratio of the crack and wrinkle structures accounts for 31.8% and 9.5%, respectively. When the sensor is stretched, the cracks fracture, the wrinkles could reduce the unrecoverable destruction of cracks, resulting in an excellent recoverability and stability. Based on introduction of the designed CWS in the sensor, the hysteresis effect is limited effectively. The CWS sensor possesses a satisfactory sensitivity(GF=750 under 24% strain), an ultralow detectable limit(strain=0.1%) and a short respond time of 90 ms. For the sensing service behaviors, the CWS sensor exhibits an ultrahigh durability(high stability>2×10^(4) stretching-releasing cycles). The excellent practicality of CWS sensor is demonstrated through various human motion tests,including vigorous exercises of various joint bending, and subtle motions of phonation, facial movements and wrist pulse. The present CWS sensor shows great developing potential in the field of cost-effective, portable and high-performance electronic skins.展开更多
Wearable sensors have attracted significant attention due to their superior sensitivity, safety, and adaptability compared with conventional detection technologies. However, developing sustainable sensing materials th...Wearable sensors have attracted significant attention due to their superior sensitivity, safety, and adaptability compared with conventional detection technologies. However, developing sustainable sensing materials that combine excellent performance with environmental friendliness remains a significant challenge. In this study, Juncus effusus (JE), a natural fiber featuring a unique internal three-dimensional (3D) network structure, was employed as the substrate. Conductive polyaniline was loaded onto the JE structure to impart electrical conductivity, and Ecoflex encapsulation provided high elasticity. Based on this approach, a JE-based resistive flexible sensor (PHE-JE) was successfully fabricated. The PHE-JE sensor exhibits high stability under various strain conditions, along with excellent flexibility and durability. Moreover, benefiting from its complex 3D structure and synergistic material interactions, the PHE-JE sensor enables accurate detection of diverse motion types, showing promising potential for future wearable sensing applications.展开更多
The flexible wearable sensors with excellent stretchability,high sensitivity and good biocompatibility are significantly required for continuously physical condition tracking in health management and rehabilitation mo...The flexible wearable sensors with excellent stretchability,high sensitivity and good biocompatibility are significantly required for continuously physical condition tracking in health management and rehabilitation monitoring.Herein,we present a high-performance wearable sensor.The sensor is prepared with nanocomposite hydrogel by using silk fibroin(SF),polyacrylamide(PAM),polydopamine(PDA)and graphene oxide(GO).It can be used to monitor body motions(including large-scale and small-scale motions)as well as human electrophysiological(ECG)signals with high sensitivity,wide sensing range,and fast response time.Therefore,the proposed sensor is promising in the fields of rehabilitation,motion monitoring and disease diagnosis.展开更多
Sandwich-structured flexible sensors based on graphene have high sensitivity and stability.When graphene is combined with a flexible substrate in a sandwich structure,the weak bonding between them compromises the sens...Sandwich-structured flexible sensors based on graphene have high sensitivity and stability.When graphene is combined with a flexible substrate in a sandwich structure,the weak bonding between them compromises the sensor's stability and sensitivity at low strains.This presents challenges in monitoring subtle physiological activities,such as hand bending and pulse rate.For this purpose,laser-induced graphene(LIG)is proposed to be used to prepare flexible sensors in order to improve the sensitivity and stability of the sensors at low strains.Polydimethylsiloxane(PDMS)with low modulus and polyimide(PI)with rich carbon content are selected as precursor materials for LIG,and graphene is formed through laser induction.Subsequently,silver nanowires(Ag NWs)solution is added to LIG to give the sensor low strain and high sensitivity performance.When the PI/PDMS ratio is 1:3,the Ag NWs/LIG flexible strain sensor exhibits excellent sensitivity(GF=778.468)over a small strain range(8.76%-11.25%).Meanwhile,the sensor still shows excellent stability after 2000 cycle experiments.The Ag NWs/LIG flexible strain sensor shows good performance when placed on the back of the hand,around the eyes,etc.It is demonstrated that Ag NWs/LIG flexible strain sensors have good application potential in human physiological activity monitoring,health management and medical fields,and provide a low-strain,high-sensitivity sensor design strategy for flexible wearable devices.展开更多
Flexible strain sensors are essential in fields such as medicine,sports,robotics,and virtual reality but face challenges in achieving excellent sensing performance and accurate multi-directional detection simultaneous...Flexible strain sensors are essential in fields such as medicine,sports,robotics,and virtual reality but face challenges in achieving excellent sensing performance and accurate multi-directional detection simultaneously.To address this issue,we have developed a spider-web structured multi-directional flexible strain sensor using Ti_(3)C_(2)T_(x)(MXene)conductive ink and three-dimensional(3D)printing technology.Combined with a multi-class,multi-output neural network model algorithm,the sensor achieves signal decoupling from the sensor array,allowing for precise detection of strain direction and intensity.It exhibits good sensitivity(gauge factor~26.3),a moderate sensing range(0%-10%),and high reliability(1000 stretching cycles).Using neural network algorithms,a four-unit spider-web sensor array achieves approximately 97% accuracy in identifying strain intensity and direction within the 0%-10% strain range under various surface stimuli.Additionally,it can track complex human motions,demonstrating significant potential in applications such as motion monitoring and human-machine interaction.展开更多
基金financially supported by National Natural Science Foundation of China(52575458,52405424,52275575)Science and Technology Programme of Fujian Province(2024J010011,2024H0002)。
文摘Temperature stability is essential for the precision of flexible sensors.However,constrained by the composite principle of heterogeneous materials,the existing self-compensating methods encounter substantial challenges.To tackle this,high-entropy alloy nanofibers were utilized to construct a flexible strain sensor with inherent temperature stability.This approach leverages the electrohydrodynamic direct writing;a precursor conductive network was established through the electrospinning of a high-entropy alloy acetate and polyvinylidene difluoride solution blend.Subsequently,annealing treatment facilitated metallization,resulting in the synergistic preservation of polymer stretchability and the low temperature coefficient of resistance properties of high-entropy alloys inside the nanofibers.The test results demonstrate that the high-entropy alloys flexible strain sensor exhibits a remarkably low temperature coefficient of resistance(45.59 ppm K^(-1))across the range of-10 to 70℃,a sensitivity coefficient GF of 1.12 with a 50%strain range,and a response time of 310 ms.After 6000 stretching cycles,no baseline drift or failure occurred,indicating excellent cyclic stability.Furthermore,the outstanding temperature stability of the sensor was validated through wearable application and robotic hands strain sensing conducted under varied environment temperatures.This work provides a viable design pathway for developing flexible sensors with an inherently low temperature coefficient of resistance.
基金support from the National Key R&D Program of China(2021YFB3200700)the National Natural Science Foundation of China(Grant No.0214100221,51925503).
文摘This study presents a breakthrough in flexible strain sensor technology with the development of an ultrahigh sensitivity and wide-range sensor,addressing the critical challenge of reconciling sensitivity with measurement range.Inspired by the structure of bamboo slips,we introduce a novel approach that utilises liquid metal to modulate the electrical pathways within a cracked platinum fabric electrode.The resulting sensor demonstrates a gauge factor greater than 108 and a strain measurement capability exceeding 100%.The integration of patterned liquid metal enables customisable tuning of the sensor’s response,while the porous fabric structure ensures superior comfort and air permeability for the wearer.Our design not only optimises the sensor’s performance but also enhances the electrical stability that is essential for practical applications.Through systematic investigation,we reveal the intrinsic mechanisms governing the sensor’s response,offering valuable insights for the design of wearable strain sensors.The sensor’s exceptional performance across a spectrum of applications,from micro-strain to large-strain detection,highlights its potential for a wide range of real-world uses,demonstrating a significant advancement in the field of flexible electronics.
基金the National Natural Science Foundation of China(Grant No.52203037,52103031,and 52073107)the Natural Science Foundation of Hubei Province of China(Grant No.2022CFB649)the National Key Research and Development Program of China(Grant No.2022YFC3901902).
文摘Liquid leakage of pipeline networks not only results in considerableresource wastage but also leads to environmental pollution and ecological imbalance.In response to this global issue, a bioinspired superhydrophobic thermoplastic polyurethane/carbon nanotubes/graphene nanosheets flexible strain sensor (TCGS) hasbeen developed using a combination of micro-extrusion compression molding andsurface modification for real-time wireless detection of liquid leakage. The TCGSutilizes the synergistic effects of Archimedean spiral crack arrays and micropores,which are inspired by the remarkable sensory capabilities of scorpions. This designachieves a sensitivity of 218.13 at a strain of 2%, which is an increase of 4300%. Additionally, it demonstrates exceptional durability bywithstanding over 5000 usage cycles. The robust superhydrophobicity of the TCGS significantly enhances sensitivity and stability indetecting small-scale liquid leakage, enabling precise monitoring of liquid leakage across a wide range of sizes, velocities, and compositionswhile issuing prompt alerts. This provides critical early warnings for both industrial pipelines and potential liquid leakage scenariosin everyday life. The development and utilization of bioinspired ultrasensitive flexible strain sensors offer an innovative and effectivesolution for the early wireless detection of liquid leakage.
基金supported by the National Natural Science Foundation of China(32071715)Canada Research Chairs program of the Government of Canada,and National Science Foundation for Post-doctoral Scientists of China(2019M651050).
文摘With the rapid development of“Internet of Things”and human-computer interaction techniques,it is essential and urgent to develop facile and scalable fabrication platforms for stretchable flexible sensor.Herein,we report a facile strategy of using the green choline chloride-acrylamide deep eutectic solvent(CC-AM DES)to guide the in-situ ring-opening polymerization ofα-lipoic acid(LA),leading to the successful development of a stretchable ionogel material.The as-prepared ionogel from CC-AM DES system exhibits multifunctional merits including the super stretchability(>9000%),100%UV-blocking ability,tunable adhesiveness(29-414 kPa),high ionic conductivity(4.45×10^(-4) S/cm),and ideal anti-freezing(-27℃).In addition,this outstanding ionogel can be readily coated on various material substrates with designable shapes and patterns.Owning to these promising properties and performances,a scalable flexible strain sensor is assembled from the ionogel and exhibits stable resistance variations(R/R_(0))towards multiple external mechanical stimulus.This study provides a green,cost effective,and scalable strategy to fabricate ionogel materials and multifunctional flexible strain sensors,showing a great potential in the fast-emerging highly stretchable wearable/flexible electronics.
基金supported by the National Natural Science Foundation of China(No.52073099)the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515010847)the Guangdong Project of R&D Plan in Key Areas(No.2020B010180001)。
文摘Elastomers with high strength and toughness,excellent self-healing properties,and biocompatibility have broad application prospects in wearable electronics and other fields,but preparing it remains a challenge.In this work,we propose a highly adaptable strategy by introducing the small molecule crosslinking agent of triethanolamine(TEA)to the poly(thioctic acid)(PTA)chains and preparing the PAx Ey elastomers using a simple synthesis step.This strategy stabilizes the PTA chains by constructing multiple non-covalent cross-linked dynamic networks,endowing materials with excellent strength and toughness(tensile strength of 288 kPa,toughness of 278.2 kJ/m3),admirable self-healing properties(self-healing efficiency of 121.6%within 7 h at 70℃),and good biocompatibility.The PAx Ey elastomers can also be combined with MWNTs to become flexible strain sensors,which can be used to monitor human joint movements with high sensitivity,repeatable responses,and stability.
基金Project(ZZYJKT2019-05)supported by State Key Laboratory of High Performance Complex Manufacturing,ChinaProject(51605497)supported by the National Natural Science Foundation of ChinaProject(2020CX05)supported by Innovation-Driven Project of Central South University,China。
文摘Conductive polymer composites(CPCs)are widely used in the flexible strain sensors due to their simple fabrication process and controllable sensing properties.However,temperature has a significance impact on the strain sensing performance of CPCs.In this paper,the strain sensing characteristics of MWCNTs/PDMS composites under temperature loading were systematically studied.It was found that the sensitivity decreased with the increase of temperature and the phenomenon of shoulder peak also decreased.Based on the theory of polymer mechanics,it was found that temperature could affect the conductive network by changing the motion degree of PDMS molecular chain,resulting in the change of sensing characteristics.Finally,a mathematical model of the resistance against loading condition(strain and temperature),associated with the force−electrical equivalent relationship of composites,was established to discuss the experimental results as well as the sensing mechanism.The results presented in this paper was believed helpful for the further application of strain sensors in different temperature conditions.
基金This research is supported by the Science and Technology Department of Jilin Province[20210202128NC]The People’s Republic of China Ministry of Science and Technology[2018YFF0213606-03]Jilin Province Development and Reform Commission[2019C021].
文摘Flexible strain sensor has attracted much attention because of its potential application in human motion detection.In this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS)with room temperature vulcanized silicone rubber(RTVS).In this paper,the formation mechanism of conductive sponge was studied.Based on the combination of carbonized sponge and RTVS,the strain sensing mechanism and piezoresistive properties are discussed.After research and testing,the CS/RTVS flexible strain sensor has excellent fast response speed and stability,and the maximum strain coefficient of the sensor is 136.27.In this study,the self-developed CS/RTVS sensor was used to monitor the movements of the wrist joint,arm elbow joint and fingers in real time.Research experiments show that CS/RTVS flexible strain sensor has good application prospects in the field of human motion monitoring.
文摘As the most intuitive way of visual signal feedback,color change is often applied by living organisms to transmit signals and resist natural enemies due to its convenient and direct characteristics.Inspired by the structure color charge of discoloration of chameleons skin,a photonic hydrogel film that can be used for flexible strain detection was developed.Fe_(3)O_(4)@C nanoparticles were used as photonic crystal units,which could self-assemble into one-dimensional chain-like structure in the hydrogel under magnetic field.The structural color of the film will change with the photonic crystal band gap,the film will produce a synergistic color change under mechanical stretching.The resulting flexible film demonstrates bright structural colors,which exhibits a wide strain response up to 120%and achieves a color dynamic change from red(λ=730 nm)to purple(λ=400 nm).In addition,the prepared film exhibits high sensitivity,short response time and good stabilization.The superior performance of flexible strain detection is attributed to the flexible large deformation and good optical properties of the hydrogel film and highly tunable grating structure of the photonic crystal.This work offers a generic approach for the development of visually responsive strain sensors,and provides a wider application prospect in mechanical sensors,stretchable optics,and diagnostics.
基金Science Foundation of National Key Laboratory of Science and Technology on Advanced Composites in Special Environments(No.JCKYS2024603C009).
文摘Flexible strain sensors have garnered significant attention for their potential applications in advanced flexible electronics and wearable technologies.However,achieving stable signal transmission at high temperatures remains a major challenge.In this study,we developed a novel polyimide(PI)aerogel composite,reinforced with intrinsically short-cut polyimide nanofibers(PINF)that are surface-coated with silver nanoparticles to enhance both conductivity and mechanical strength.Carbon nanotubes(CNTs)are used as the main filler in synergistic effect with Ag@PINF particles to further improve the conductivity and sensing performance of the composite material.This synergistic design results in a flexible PI aerogel composite material with rapid response time(116 ms),high sensitivity(GF=3.12),and long-term cycling stability(>1000 cycles).Additionally,the sensing materials were tested at high temperatures and after high-temperature aging,demonstrating good flexible sensing performance.Experimental results demonstrate that the composite sensor maintains stable strain-sensing performance across a range of environmental temperatures,showing consistent strain response under the same deformation conditions.This work provides a promising approach for fabricating high-performance,temperature-resistant flexible strain sensors,with broad applications in flexible electronics and wearable technologies.
基金supported by the National Natural Science Foundation of China(No.62288102,62371397,62304182,and 62471396)the Fundamental Research Funds for the Central Universities,the Young Talent Fund of Xi’an Association for Science and Technology(No.959202413089)Engineering Research Center of Flexible Electronics,Universities of Shaanxi Province,and Open Test Funding Project from Analytical&Testing Center of Northwestern Polytechnical University(No.2023T008).
文摘Flexible strain sensors with high sensitivity and stability at high temperatures are significantly desirable for their accurate and long-term signal detection in wearable devices,environment monitoring,and aerospace electronics.Despite the considerable efforts in materials development and structural design,it remains a challenge to develop highly sensitive,flexible strain sensors operating at high temperatures due to the trade-off between sensitivity and stability for the representative sensing materials.Herein,we develop a high-temperature flexible sensor using Mo_(x)W_(1-x)S_(2) alloy films.A pulsed laser is introduced to directly synthesize Mo_(x)W_(1-x)S_(2) patterns with controllable compositions and physical parameters,enabling the realization of flexible sensors without photolithography or transfer procedures.The resultant flexible sensors exhibit a high gauge factor of 97.4,a low strain detection of 4.9με,and strong tolerance to a temperature of 500℃.Owing to its superior performance,we develop a wireless acoustic recognition system to distinguish tiny strain signals of tuning forks with a vibration frequency up to 128 Hz under extreme temperature conditions.The laser method for the direct fabrication of Mo_(x)W_(1-x)S_(2) alloy-based flexible sensors holds great potential in the precise detection of strain signals from complex structures at high temperatures.
基金supported by the National Natural Science Foundation of China (62301291)Taishan Scholars Project Special Funds (tsqn202312035)。
文摘Smart agriculture utilizes sensors and software to control agricultural production through mobile or computer platforms,enabling unmanned,automated,and intelligent management.Recently,research and development in plant growth monitoring technologies have garnered significant attention.The challenge lies in achieving long-term monitoring,phased predictions,and plant self-regulation without harming the plants.The present study demonstrates the fabrication of plant-compatible and breathable tensile and bending strain sensors using composite nanofiber membranes(CNMs)composed of Ti_(2)C_(2)T_(x)(MXene),carbon nanotubes(CNTs),and thermoplastic polyurethanes(TPU)through electrospinning and ultrasonic immersion techniques.The MXene and CNTs synergistically form a dual-network conductive structure on the TPU nanofiber membrane,thereby imparting the composite membrane with remarkable tensile sensitivity(5.41,7.39,and 3.39 within the ranges of 0%-20%,20%-50%,and 50%-70%,respectively)as well as exceptional bending sensitivity(1.79,0.89,and 0.46 within the ranges of 0°-30°,30°-90°,and 90°-120°,respectively).The tensile strain sensor,combined with a deep learning Long Short-Term Memory(LSTM)model,establishes a platform for plant growth monitoring and prediction.The bending strain sensor,integrated with a shape memory alloy(SMA)-based soft actuator,forms a plant sensing-actuating system to assist in plant leaf growth.This work leverages MXene/CNTs/TPU CNMs to flexibly prepare strain sensors for specific applications,combining deep learning and soft actuators to achieve plant growth prediction and self-regulation.This research holds significant importance in advancing the development of smart agriculture.
基金supported by the Start-Up Funds for Outstanding Talents in Central South University through Project Nos.202045007 and 202044017.
文摘Carbon fibre(CF)embedded into elastomeric media has been attracting incredible interest as flexible strain sensors in the application of skin electronics owing to their high sensitivity in a very small strain gauge.To further improve the sensitivity of CF/PDMS composite strain sensor,the relatively low temperature prepared TiO_(2) nanowire via hydrothermal route was employed herein to functionalize CF.The results showed a significant increase in the sensitivity of the TiO_(2)@CF/PDMS composite strain sensors which was reflected by the calculated gauge factor.As the prepared TiO_(2) nanowire vertically embraced the surroundings of the CF,the introduced TiO_(2) nanowire contributed to a highly porous structure which played a predominant role in improving the sensitivity of strain sensors.Moreover,the significant strain rate dependent behavior of TiO_(2)@CF/PDMS strain sensor was revealed when performing monotonic tests at varied strain rate.Therefore,introducing TiO_(2) nanowire on CF offers a new technique for fabricating flexible strain sensors with improved sensitivity for the application of flexible electronics.
基金supported by the National Natural Science Foundation of China(Nos.52373093 and 12072325)the Outstanding Youth Fund of Henan Province(No.242300421062)+1 种基金National Key R&D Program of China(No.2019YFA0706802)the 111 project(No.D18023).
文摘With the rapid development of wearable electronic skin technology, flexible strain sensors have shown great application prospects in the fields of human motion and physiological signal detection, medical diagnostics, and human-computer interaction owing to their outstanding sensing performance. This paper reports a strain sensor with synergistic conductive network, consisting of stable carbon nanotube dispersion (CNT) layer and brittle MXene layer by dip-coating and electrostatic self-assembly method, and breathable three-dimensional (3D) flexible substrate of thermoplastic polyurethane (TPU) fibrous membrane prepared through electrospinning technology. The MXene/CNT@PDA-TPU (MC@p-TPU) flexible strain sensor had excellent air permeability, wide operating range (0–450 %), high sensitivity (Gauge Factor, GFmax = 8089.7), ultra-low detection limit (0.05 %), rapid response and recovery times (40 ms/60 ms), and excellent cycle stability and durability (10,000 cycles). Given its superior strain sensing capabilities, this sensor can be applied in physiological signals detection, human motion pattern recognition, and driving exoskeleton robots. In addition, MC@p-TPU fibrous membrane also exhibited excellent photothermal conversion performance and can be used as a wearable photo-heater, which has far-reaching application potential in the photothermal therapy of human joint diseases.
基金China Postdoctoral Science Foundation(Grant No.2021M700773)the Jiangsu Planned Projects for Postdoctoral Research Funds(Grant No.2021K509C)。
文摘Flexible strain sensors have been extensively used in human motion detection,medical aids,electronic skins,and other civilian or military fields.Conventional strain sensors made of metal or semiconductor materials suffer from insufficient stretchability and sensitivity,imposing severe constraints on their utilization in wearable devices.Herein,we design a flexible strain sensor based on biphasic hydrogel via an in-situ polymerization method,which possesses superior electrical response and mechanical performance.External stress could prompt the formation of conductive microchannels within the biphasic hydrogel,which originates from the interaction between the conductive water phase and the insulating oil phase.The device performance could be optimized by carefully regulating the volume ratio of the oil/water phase.Consequently,the flexible strain sensor with oil phase ratio of 80%demonstrates the best sensitivity with gauge factor of 33 upon a compressive strain range of 10%,remarkable electrical stability of 100 cycles,and rapid resistance response of 190 ms.Furthermore,the human motions could be monitored by this flexible strain sensor,thereby highlighting its potential for seamless integration into wearable devices.
基金financially supported by the National Natural Science Foundation of China(No.22271074)Natural Science Foundation of Hebei Province(Nos.B2023208042,B2022208032,B2021208066,E2024208084,and E2024208088)+2 种基金Science Research Project of Hebei Education Department(No.JZX2024013)Special Fund for Local Scientific and Technological Development under the Guidance of the Central Government(No.236Z3704G)Hebei Province High Level Talent Funding(No.A202001010)。
文摘Owing to their good biocompatibility,polysaccharide hydrogels have broad application prospects in the field of flexible strain sensors.However,there are still significant challenges in the preparation of polysaccharide hydrogels with good mechanical properties.MCA-Li Cl hydrogels were prepared by introducing methacrylated hyaluronic acid(Me HA)into the polymer network in the presence of acrylic acid(AA),acryloyloxyethyltrimethyl ammonium chloride(CATAC),and metal ions.The polymer network not only has a chemically cross-linked network and a tough network structure,but also benefits from a variety of supramolecular interactions,such as hydrogen bonding and coordination covalent bonding,resulting in excellent mechanical properties,with an elongation at break of 1390%,a tensile strength of up to 1200 k Pa,a toughness of 9.4546 MJ/m^(3),and adhesive properties towards various substrates.At the same time,the hydrogel has a high conductivity(5.33 mS/cm)and high strain-sensing sensitivity(Gauge factor=2.55).The flexible strain sensor assembled from the prepared MCA-Li Cl hydrogel can be used to detect human movements,from micro-expressions(smiles,swallowing)to pulse signals and other physiological activities,as well as large-scale joint movements(wrists,elbows,knees,fingers,etc.),realizing the real-time monitoring of full-scale human movements.The prepared hydrogels have potential applications in wearable devices,electronic skin,and strain-sensor components.
基金financially supported by the National Natural Science Foundation of China (Nos. 51773183 and U1804133)National Natural Science Foundation of China-Henan Province Joint Funds (No. U1604253)+1 种基金Henan Province University Innovation Talents Support Program (No. 20HASTIT001)Innovation Team of Colleges and Universities in Henan Province(No. 20IRTSTHN002)。
文摘Flexible strain sensor has promising features in successful application of health monitoring, electronic skins and smart robotics, etc.Here, we report an ultrasensitive strain sensor with a novel crack-wrinkle structure(CWS) based on graphite nanoplates(GNPs)/thermoplastic urethane(TPU)/polydimethylsiloxane(PDMS) nanocomposite. The CWS is constructed by pressing and dragging GNP layer on TPU substrate,followed by encapsulating with PDMS as a protective layer. On the basis of the area statistics, the ratio of the crack and wrinkle structures accounts for 31.8% and 9.5%, respectively. When the sensor is stretched, the cracks fracture, the wrinkles could reduce the unrecoverable destruction of cracks, resulting in an excellent recoverability and stability. Based on introduction of the designed CWS in the sensor, the hysteresis effect is limited effectively. The CWS sensor possesses a satisfactory sensitivity(GF=750 under 24% strain), an ultralow detectable limit(strain=0.1%) and a short respond time of 90 ms. For the sensing service behaviors, the CWS sensor exhibits an ultrahigh durability(high stability>2×10^(4) stretching-releasing cycles). The excellent practicality of CWS sensor is demonstrated through various human motion tests,including vigorous exercises of various joint bending, and subtle motions of phonation, facial movements and wrist pulse. The present CWS sensor shows great developing potential in the field of cost-effective, portable and high-performance electronic skins.
基金supported by the National Natural Science Foundation of China(52303064,Xia L)Natural Science Foundation of Hubei Province(2025AFB867,Xia L)。
文摘Wearable sensors have attracted significant attention due to their superior sensitivity, safety, and adaptability compared with conventional detection technologies. However, developing sustainable sensing materials that combine excellent performance with environmental friendliness remains a significant challenge. In this study, Juncus effusus (JE), a natural fiber featuring a unique internal three-dimensional (3D) network structure, was employed as the substrate. Conductive polyaniline was loaded onto the JE structure to impart electrical conductivity, and Ecoflex encapsulation provided high elasticity. Based on this approach, a JE-based resistive flexible sensor (PHE-JE) was successfully fabricated. The PHE-JE sensor exhibits high stability under various strain conditions, along with excellent flexibility and durability. Moreover, benefiting from its complex 3D structure and synergistic material interactions, the PHE-JE sensor enables accurate detection of diverse motion types, showing promising potential for future wearable sensing applications.
基金Smart Medicine Research Project of Chongqing Medical University in 2020(YJSZHYX202022)Smart Medicine Research Project of Chongqing Medical University(ZHYX2019019)Chongqing Research Program of Basic Research and Frontier Technology(cstc2018jcyjAX0165).
文摘The flexible wearable sensors with excellent stretchability,high sensitivity and good biocompatibility are significantly required for continuously physical condition tracking in health management and rehabilitation monitoring.Herein,we present a high-performance wearable sensor.The sensor is prepared with nanocomposite hydrogel by using silk fibroin(SF),polyacrylamide(PAM),polydopamine(PDA)and graphene oxide(GO).It can be used to monitor body motions(including large-scale and small-scale motions)as well as human electrophysiological(ECG)signals with high sensitivity,wide sensing range,and fast response time.Therefore,the proposed sensor is promising in the fields of rehabilitation,motion monitoring and disease diagnosis.
基金supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZDK202300606)Chongqing Municipal Natural Science Foundation(Grant No.CSTB2022NSCQ-MSX0380)+1 种基金National High-end Foreign Experts Introduction Plan(Grant No.G2022035005L)Chongqing Talent Plan of Overall Rationing System Project(Grant No.CQYC202203091156)。
文摘Sandwich-structured flexible sensors based on graphene have high sensitivity and stability.When graphene is combined with a flexible substrate in a sandwich structure,the weak bonding between them compromises the sensor's stability and sensitivity at low strains.This presents challenges in monitoring subtle physiological activities,such as hand bending and pulse rate.For this purpose,laser-induced graphene(LIG)is proposed to be used to prepare flexible sensors in order to improve the sensitivity and stability of the sensors at low strains.Polydimethylsiloxane(PDMS)with low modulus and polyimide(PI)with rich carbon content are selected as precursor materials for LIG,and graphene is formed through laser induction.Subsequently,silver nanowires(Ag NWs)solution is added to LIG to give the sensor low strain and high sensitivity performance.When the PI/PDMS ratio is 1:3,the Ag NWs/LIG flexible strain sensor exhibits excellent sensitivity(GF=778.468)over a small strain range(8.76%-11.25%).Meanwhile,the sensor still shows excellent stability after 2000 cycle experiments.The Ag NWs/LIG flexible strain sensor shows good performance when placed on the back of the hand,around the eyes,etc.It is demonstrated that Ag NWs/LIG flexible strain sensors have good application potential in human physiological activity monitoring,health management and medical fields,and provide a low-strain,high-sensitivity sensor design strategy for flexible wearable devices.
基金supported by the National Natural Science Foundation of China(Nos.52422505 and 12274124)the Shanghai Pilot Program for Basic Research(No.22TQ1400100-6)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Innovative Research Group Project of the National Natural Science Foundation of China(No.52321002).
文摘Flexible strain sensors are essential in fields such as medicine,sports,robotics,and virtual reality but face challenges in achieving excellent sensing performance and accurate multi-directional detection simultaneously.To address this issue,we have developed a spider-web structured multi-directional flexible strain sensor using Ti_(3)C_(2)T_(x)(MXene)conductive ink and three-dimensional(3D)printing technology.Combined with a multi-class,multi-output neural network model algorithm,the sensor achieves signal decoupling from the sensor array,allowing for precise detection of strain direction and intensity.It exhibits good sensitivity(gauge factor~26.3),a moderate sensing range(0%-10%),and high reliability(1000 stretching cycles).Using neural network algorithms,a four-unit spider-web sensor array achieves approximately 97% accuracy in identifying strain intensity and direction within the 0%-10% strain range under various surface stimuli.Additionally,it can track complex human motions,demonstrating significant potential in applications such as motion monitoring and human-machine interaction.
