The complex wiring,bulky data collection devices,and difficulty in fast and on-site data interpretation significantly limit the practical application of flexible strain sensors as wearable devices.To tackle these chal...The complex wiring,bulky data collection devices,and difficulty in fast and on-site data interpretation significantly limit the practical application of flexible strain sensors as wearable devices.To tackle these challenges,this work develops an artificial intelligenceassisted,wireless,flexible,and wearable mechanoluminescent strain sensor system(AIFWMLS)by integration of deep learning neural network-based color data processing system(CDPS)with a sandwich-structured flexible mechanoluminescent sensor(SFLC)film.The SFLC film shows remarkable and robust mechanoluminescent performance with a simple structure for easy fabrication.The CDPS system can rapidly and accurately extract and interpret the color of the SFLC film to strain values with auto-correction of errors caused by the varying color temperature,which significantly improves the accuracy of the predicted strain.A smart glove mechanoluminescent sensor system demonstrates the great potential of the AIFWMLS system in human gesture recognition.Moreover,the versatile SFLC film can also serve as a encryption device.The integration of deep learning neural network-based artificial intelligence and SFLC film provides a promising strategy to break the“color to strain value”bottleneck that hinders the practical application of flexible colorimetric strain sensors,which could promote the development of wearable and flexible strain sensors from laboratory research to consumer markets.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
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
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
Conductive hydrogels derived from natural polymers have attracted increasing attention in wearable electronics due to their inherent biocompatibility and sustainability.However,their poor mechanical strength,limited c...Conductive hydrogels derived from natural polymers have attracted increasing attention in wearable electronics due to their inherent biocompatibility and sustainability.However,their poor mechanical strength,limited conductivity and unsatisfactory environmental adaptability remain significant challenges fo r practical applications.In this study,we report a high-performance gelatin-based conductive hydrogel(GPC)reinforced with polypyrrole-decorated cellulose nanofibers(PPy@CNF)and enhanced by a zwitterionic betaine/(NH_(4))_(2)SO_(4) solution.The PPy@CNF hybrid nanofillers were synthesized via in situ oxidative polymerization,enabling homogeneous dispersion of PPy along the CNF su rface.The incorporation of PPy@CNF significantly improved both mechanical strength and conductivity of the gelatin hydrogel.Meanwhile,the Hofmeister effect induced by(NH_(4))_(2)SO_(4) strengthened the hydrogel network,and the introduction of betaine further enhanced its anti-freezing and moisture-retention properties.The optimized GPC hydrogel exhibited a high tensile strength of 1.02 MPa,conductivity of 1.5 S·m^(-1),and stable performance at temperatures down to-50℃.Furthermore,it was successfully assembled into a wearable strain sensor for real-time human motion monitoring,and as an electrode layer in a flexible triboelectric nanogenerator(TENG),enabling biomechanical energy harvesting and self-powered sensing.This work provides a promising strategy for developing sustainable,multifu nctional hydrogels for next-generation weara ble electronics.展开更多
Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensin...Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensing ability are urgently required for the precise measurement of large and high-frequency dynamic deformations.However,the existing hysteresis of the current functional materials utilized in strain sensors significantly impedes the achievement of these properties.Herein,we introduce an ultralow dynamic hysteresis capacitive strain sensor using a low-hysteresis and high-relative-permittivity ionic liquid-elastomer composite as the dielectric material.Based on the low-hysteresis dielectric,the prepared capacitive strain sensors exhibit ultralow electrical hysteresis(2.20%at a strain rate of 100% s^(-1)and strain of100%)and maintain low electrical hysteresis(4.35%)even under extremely high strain rates and large dynamic strain loads(a strain rate of 500% s^(-1)and strain of 100%).Moreover,the strain sensor manifests exceptional cyclic stability under 50,000 cycles of 100%strain at a strain rate of 200% s^(-1);the response curves remain nearly identical throughout these 50,000 cycles.Furthermore,the ultralowhysteresis strain sensor was successfully applied to accurate and reliable real-time human-machine interactions,revealing its great potential in various fields,including electronic skin,flexible robotics,wearable electronics,and virtual reality.展开更多
Eutectogels are considered to have immense application potential in the field of flexible wearable ionotronic devices because of their excellent ionic conductivity,thermal and electrochemical stability,and non-volatil...Eutectogels are considered to have immense application potential in the field of flexible wearable ionotronic devices because of their excellent ionic conductivity,thermal and electrochemical stability,and non-volatility.However,most existing technologies still struggle to achieve synergistic optimization of key performance indicators,such as high mechanical strength and ionic conductivity.To address this chal-lenge,this study successfully prepared a green eutectogel material with outstanding comprehensive properties by leveraging the high solubility of glycerol in a polymerizable deep eutectic solvent(DES)composed of acrylic acid and choline chloride.The resulting eutectogels exhibited a high transparency(89%),high mechanical strength(up to 2.8 MPa),and exceptional tensile performance(up to 1385%).The fabricated flexible sensor demonstrated ideal linear sensitivity(gauge factor:0.88),a broad response range(1%-100%),and reliable stability(over 1000 cycles),en-abling the precise monitoring of human motion(e.g.,finger bending and wrist rotation).The flexible strain sensor based on this eutectogel is ex-pected to show promising prospects for medical monitoring,human-machine interaction,and industrial sensing applications.展开更多
As a natural biopolymer material,silk fibroin with unique mechanical properties can be used in the preparation of biocomposite hydrogels for strain sensors.But,the electromechanical properties of bio-composite hydroge...As a natural biopolymer material,silk fibroin with unique mechanical properties can be used in the preparation of biocomposite hydrogels for strain sensors.But,the electromechanical properties of bio-composite hydrogel strain sensors are still insufficient,such as the deterioration of electrical signals and low sensitivity,which need to develop a hydrogel with a stable transmission network for electric con-duction.Herein,a silk fibroin biocomposite hydrogel is prepared by incorporating tannic acid and MXene nanosheets into a polyacrylamide and silk fibroin double network.The electromechanical properties of hydrogels are improved by optimizing the proportion of material components.As a result,the double network structure and supramolecular interaction enhance the stretchability of hydrogels(692% fracture strain).The hydrogel also exhibits good biocompatibility and conductivity(0.85 S/m),which shows the application prospect in wearable sensors.The wireless strain sensor assembled by this biocomposite hy-drogel presents good portability and sensing performance,such as high sensitivity(gauge factor=6.04),wide working range(500% strain),and outstanding stability(1000 cycles at 100%strain).The results in-dicate that the hydrogel strain sensor can be used to monitor human body movement.The biocomposite hydrogel is expected to be applied in the field of wearable strain sensors,and this study can provide a new way for the design of flexible electronic materials.展开更多
Flexible wearable electronic devices based on hydrogels have immense potential in a wide range of applications.However,many existing strain sensors suffer from significant limitations including poor mechanical propert...Flexible wearable electronic devices based on hydrogels have immense potential in a wide range of applications.However,many existing strain sensors suffer from significant limitations including poor mechanical properties,low adhesion,and insufficient conductivity.To address these challenges,this study successfully developed an organic-inorganic double-network conductive hydrogel using acrylic-modified bentonite (AABT) as a key component.The incorporation of AABT significantly enhanced the mechanical properties of the ATHG@LiCl hydrogel,achieving an impressive stretchability of 4000% and tensile strength of 250 kPa.Moreover,it improved the electrical conductivity of the hydrogel to a maximum of 1.53 mS/cm.The catechol structure of tannic acid (TA) further augmented the adhesive properties of the ATHG@LiCl hydrogel toward various substrates such as copper,iron,glass,plastic,wood,and pigskin.The addition of lithium chloride (LiCl) and dimethyl sulfoxide(DMSO) endowed the hydrogel with exceptional freezing resistance and flexibility,even at low temperatures of-20℃.Remarkably,the hydrogel maintained a conductivity of 0.53 mS/cm under these conditions,surpassing the performance of many other reported hydrogels.Furthermore,the ATHG@LiCl hydrogel demonstrated outstanding characteristics,such as high sensitivity (gauge factor GF=4.50),excellent transparency (90%),and reliable strain-sensing capabilities,indicating that the ATHG@LiCl hydrogel is a highly promising candidate for flexible wearable soft materials,offering significant advancements in both functionality and performance.展开更多
Hydrogels possess significant potential for the development of multifunctional soft materials in smart sensors and wearable devices,attributed to their distinctive properties of softness,conductivity,and biocompatibil...Hydrogels possess significant potential for the development of multifunctional soft materials in smart sensors and wearable devices,attributed to their distinctive properties of softness,conductivity,and biocompatibility.Nevertheless,their widespread application is frequently limited by inadequate mechanical strength and strain capacity.This study introduces a meticulously engineered hydrogel system,LM/SA/P(AAM-co-BMA),which integrates eutectic gallium-indium alloy(EGaIn)as both a polymerization initiator and a flexible filler.The resultant hydrogel demonstrates remarkable tensile strain capabilities of up to 2800% and a tensile strength of 2.3 MPa,achieved through a synergistic interplay of ionic coordination,hydrogen bonding,and physical polymer interactions.Furthermore,the hydrogel exhibits outstanding biocompatibility,recyclability,and stable long-term storage,rendering it an ideal candidate for the continuous monitoring of high-intensity physical activities.展开更多
The fexible strain sensor has found widespread application due to its excellent fexibility,extensibility,and adaptability to various scenarios.This type of sensors face challenges in direction identification owing to ...The fexible strain sensor has found widespread application due to its excellent fexibility,extensibility,and adaptability to various scenarios.This type of sensors face challenges in direction identification owing to strong coupling between the principal strain and transverse resistance.In this study,a silver nanowires(Ag-NWs)/polydimethylsiloxane(PDMS)strain sensor was developed,using a filtration method for preparing the AgNWs film which was then combined with PDMS to create a unidirectional,highly sensitive,fast-responsive,and linear fexible strain sensor.When the grid width is 0.25 mm,the AgNWs/PDMS strain sensor demonstrates an outstanding unidirectional sensitivity,with a strain response solely along the parallel direction of the grid lines(noise ratioα≈8%),and a fast reaction time of roughly 106.99 ms.In the end,this sensor's ability to detect curvature was also demonstrated through LEDs,demonstrating its potential applications in various fields,including automotive,medical,and wearable devices.展开更多
High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for t...High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for their use.Here,this issue is addressed by creating a composite ink that combines Pb_(2)Ru_(2)O_(6) and TiB_(2) using polysilazane(PSZ)as a binder.After direct writing and annealing the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film at 800℃ in air,the resulting thin film exhibits a low temperature coefficient of resistance(TCR)of only 281 ppm/℃ over a wide temperature range from 100℃ to 700℃,while also demonstrating high sensitivity with a gauge factor approaching 19.8.This exceptional performance is attributed to the intrinsic properties of Pb_(2)Ru_(2)O_(6),which has positive TCR at high temperature,and TiB2,which has negative TCR at high temperature.Combining these materials reduces the overall TCR of the film.Tests showed that the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film maintains stable strain responses and significant signal output even under varying temperature.These findings provide valuable insights for developing high-temperature strain sensors with low TCR and high sensitivity,highlighting their potential for applications in high-temperature strain measurements.展开更多
The distributed strain sensor has significant application in real time measurement of strain status for large and important engineering structures such as aircraft, bridge and dam. In this paper, a quasi distributed...The distributed strain sensor has significant application in real time measurement of strain status for large and important engineering structures such as aircraft, bridge and dam. In this paper, a quasi distributed optical fiber strain sensor system is set up using optical time domain reflect technique. The local strain sensors based on a novel microbend configuration are designed and applied to measure local strains along the optical fiber. As the result of the experimental research, the microbend sensors show high sensitivity, good linearity and repeatability in certain operation range.展开更多
In recently years,high-performance wearable strain sensors have attracted great attention in academic and industrial.Herein,a conductive polymer composite of electrospun thermoplastic polyurethane(TPU)fibrous film mat...In recently years,high-performance wearable strain sensors have attracted great attention in academic and industrial.Herein,a conductive polymer composite of electrospun thermoplastic polyurethane(TPU)fibrous film matrix-embedded carbon black(CB)particles with adjustable scaffold network was fabricated for high-sensitive strain sensor.This work indicated the influence of stereoscopic scaffold network structure built under various rotating speeds of collection device in electrospinning process on the electrical response of TPU/CB strain sensor.This structure makes the sensor exhibit combined characters of high sensitivity under stretching strain(gauge factor of 8962.7 at 155%strain),fast response time(60 ms),outstanding stability and durability(>10,000 cycles)and a widely workable stretching range(0–160%).This high-performance,wearable,flexible strain sensor has a broad vision of application such as intelligent terminals,electrical skins,voice measurement and human motion monitoring.Moreover,a theoretical approach was used to analyze mechanical property and a model based on tunneling theory was modified to describe the relative change of resistance upon the applied strain.Meanwhile,two equations based from this model were first proposed and offered an effective but simple approach to analyze the change of number of conductive paths and distance of adjacent conductive particles.展开更多
Wearable strain sensors are arousing increasing research interests in recent years on account of their potentials in motion detection,personal and public healthcare,future entertainment,man-machine interaction,artific...Wearable strain sensors are arousing increasing research interests in recent years on account of their potentials in motion detection,personal and public healthcare,future entertainment,man-machine interaction,artificial intelligence,and so forth.Much research has focused on fiber-based sensors due to the appealing performance of fibers,including processing flexibility,wearing comfortability,outstanding lifetime and serviceability,low-cost and large-scale capacity.Herein,we review the latest advances in functionalization and device fabrication of fiber materials toward applications in fiber-based wearable strain sensors.We describe the approaches for preparing conductive fibers such as spinning,surface modification,and structural transformation.We also introduce the fabrication and sensing mechanisms of state-of-the-art sensors and analyze their merits and demerits.The applications toward motion detection,healthcare,man-machine interaction,future entertainment,and multifunctional sensing are summarized with typical examples.We finally critically analyze tough challenges and future remarks of fiber-based strain sensors,aiming to implement them in real applications.展开更多
Flexible multidirectional strain sensors are crucial to accurately determining the complex strain states involved in emerging sensing applications.Although considerable efforts have been made to construct anisotropic ...Flexible multidirectional strain sensors are crucial to accurately determining the complex strain states involved in emerging sensing applications.Although considerable efforts have been made to construct anisotropic structures for improved selective sensing capabilities,existing anisotropic sensors suffer from a trade-off between high sensitivity and high stretchability with acceptable linearity.Here,an ultrasensitive,highly selective multidirectional sensor is developed by rational design of functionally different anisotropic layers.The bilayer sensor consists of an aligned carbon nanotube(CNT)array assembled on top of a periodically wrinkled and cracked CNT-graphene oxide film.The transversely aligned CNT layer bridge the underlying longitudinal microcracks to effectively discourage their propagation even when highly stretched,leading to superior sensitivity with a gauge factor of 287.6 across a broad linear working range of up to 100%strain.The wrinkles generated through a pre-straining/releasing routine in the direction transverse to CNT alignment is responsible for exceptional selectivity of 6.3,to the benefit of accurate detection of loading directions by the multidirectional sensor.This work proposes a unique approach to leveraging the inherent merits of two cross-influential anisotropic structures to resolve the trade-off among sensitivity,selectivity,and stretchability,demonstrating promising applications in full-range,multi-axis human motion detection for wearable electronics and smart robotics.展开更多
Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical m...Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers(MNFs)embedded in a polydimethylsiloxane(PDMS)film is proposed.The strain sensor exhibits a gauge factor as high as 64.5 for strain≤0.5%and a strain resolution of 0.0012%which corresponds to elongation of 120 nm on a 1 cm long device.As a proof-of-concept,highly sensitive fingertip pulse measurement is realized.The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^(−1) enable the sensor for sound detection.Such versatile sensor could be of great use in physiological signal monitoring,voice recognition and micro-displacement detection.展开更多
The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydro...The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydrogel sensors,which can guarantee good accuracy,comfort and long service life.However,it is still a challenge to achieve simultaneous self-healing and self-adhesion in different environments(in the air,underwater and at low temperatures).Herein,a feasible new strategy was successfully carried out to prepare a starch-based composite conductive organohydrogel based on the reversible borate ester bonds formed by complexing starch/polyvinyl alcohol(PVA)/tea polyphenol(TP)with borax,and multiple hydrogen-bond interactions among PVA,starch,TP and ethylene glycol(EG).Silver nanoparticles(Ag-NPs),reduced and stabilized by TP,and MWCNTs(multi-walled carbon nanotubes)were introduced into the cross-linking networks to endow the resulting PBSTCE organohydrogel with considerable antibacterial property and conductivity,respectively.The organohydrogel possessed rapid self-healing(HE(self-healing efficiency)=96.07%in 90 s,both in the air and underwater,also at-20℃),considerable self-adhesion(both in the air and underwater,also at-20℃),remarkable stretchability(814%of elongation),anti-freezing(-20℃)and moisture-retention abilities,antibacterial activity,sensitive pH/sugar-responsiveness,and plasticity.The strain sensor formed by the PBSTCE organohydrogel can not only effectively record large-scale human motions(e.g.finger/wrist/elbow bending,walking,etc.),but also accurately capture subtle motion changes(e.g.breathing,chewing,swallowing,speaking,smiling and frowning).Moreover,the self-healed organohydrogel sensor also exhibited almost invariable mechanical,electrical and sensing behaviors.This work demonstrates a feasible strategy to construct multifunctional starch-based organohy-drogels,and promotes their efficient,stable and eco-friendly application as flexible wearable devices.展开更多
We report the direct joining of carbon nanofibers(CNFs)to silver nanowire(Ag NWs)by controlled irradiation with femtosecond(fs)laser pulses.Two separate types of nano-junction dependent on joint geometry,laser fluence...We report the direct joining of carbon nanofibers(CNFs)to silver nanowire(Ag NWs)by controlled irradiation with femtosecond(fs)laser pulses.Two separate types of nano-junction dependent on joint geometry,laser fluence and irradiation time are identified in irradiated mixtures.In one type of junction,the tip of an Ag NW is melted and flows to form a bond with an adjacent CNF.The second type of junction occurs without significant heating of the Ag NW and involves the softening and flow of carbon in the CNF in response to the transfer of plasmonic energy from the Ag NW into the CNF.Bonding in a T-type joint configuration can be of either kind depending on the relative orientation of the incident optical field and the long axis of the Ag NW.FDTD simulations were used to explore this effect for different joint geometries and laser polarization.The electrical properties of a heterojunction involving a single Ag NW-CNF structure have been measured,and it is found that the junction resistance can be reduced by six orders of magnitude after laser joining.Finally,we have investigated the properties of a strain sensor based on an Ag NW-CNF hybrid nanowire network and find that this device can exhibit high sensitivity.This sensitivity occurs as nano-junctions induced by fs laser irradiation greatly reduces the initial resistance.This laser-based technique for direct nanojoining of CNF and Ag NWs may enable the design of robust nanowire structures for application in a variety of new devices.展开更多
Multifunctional flexible devices for human motion detection and thermal management raised great at-tention as the problem of the aging population is becoming more and more serious.However,it is still a challenge to en...Multifunctional flexible devices for human motion detection and thermal management raised great at-tention as the problem of the aging population is becoming more and more serious.However,it is still a challenge to endow the devices with excellent stability and wide application scope.Here we prepared a hydrophobic and conductive fabric-based strain sensor for smart fabric via successively coating with poly-dopamine(PDA),polyaniline(PANI),polypyrrole(PPy),and polydimethylsiloxane(PDMS)through in-situ polymerization and dip-coating,which could be used for strain sensor and wearable heater both in air and underwater.The obtained sample exhibited a fast electrical response in 500 ms and could withstand 10,000 times stretching-releasing cycles,additionally,the sample exhibited satisfactory electro-thermal and photo-thermal performances.As a whole,the multifunctional fabric-based devices with excellent performances show great potential to be applied in medical monitoring and personal care,especially for aged and disabled persons.展开更多
基金funded by the National Natural Science Foundation of China(52475580)the Special Foundation of the Taishan Scholar Project(tsqn202211077,tsqn202311077)+3 种基金Shandong Provincial Excellent Overseas Young Scholar Foundation(2023HWYQ-069)the Shandong Provincial Natural Science Foundation(ZR2023ME118,ZR2023QF080)the Natural Science Foundation of Qingdao City(23-2-1-219-zyyd-jch,23-2-1-111-zyyd-jch)the Fundamental Research Funds for the Central Universities(23CX06032A).
文摘The complex wiring,bulky data collection devices,and difficulty in fast and on-site data interpretation significantly limit the practical application of flexible strain sensors as wearable devices.To tackle these challenges,this work develops an artificial intelligenceassisted,wireless,flexible,and wearable mechanoluminescent strain sensor system(AIFWMLS)by integration of deep learning neural network-based color data processing system(CDPS)with a sandwich-structured flexible mechanoluminescent sensor(SFLC)film.The SFLC film shows remarkable and robust mechanoluminescent performance with a simple structure for easy fabrication.The CDPS system can rapidly and accurately extract and interpret the color of the SFLC film to strain values with auto-correction of errors caused by the varying color temperature,which significantly improves the accuracy of the predicted strain.A smart glove mechanoluminescent sensor system demonstrates the great potential of the AIFWMLS system in human gesture recognition.Moreover,the versatile SFLC film can also serve as a encryption device.The integration of deep learning neural network-based artificial intelligence and SFLC film provides a promising strategy to break the“color to strain value”bottleneck that hinders the practical application of flexible colorimetric strain sensors,which could promote the development of wearable and flexible strain sensors from laboratory research to consumer markets.
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financially supported by the PhD research startup foundation of China West Normal University(No.22kE038)。
文摘Conductive hydrogels derived from natural polymers have attracted increasing attention in wearable electronics due to their inherent biocompatibility and sustainability.However,their poor mechanical strength,limited conductivity and unsatisfactory environmental adaptability remain significant challenges fo r practical applications.In this study,we report a high-performance gelatin-based conductive hydrogel(GPC)reinforced with polypyrrole-decorated cellulose nanofibers(PPy@CNF)and enhanced by a zwitterionic betaine/(NH_(4))_(2)SO_(4) solution.The PPy@CNF hybrid nanofillers were synthesized via in situ oxidative polymerization,enabling homogeneous dispersion of PPy along the CNF su rface.The incorporation of PPy@CNF significantly improved both mechanical strength and conductivity of the gelatin hydrogel.Meanwhile,the Hofmeister effect induced by(NH_(4))_(2)SO_(4) strengthened the hydrogel network,and the introduction of betaine further enhanced its anti-freezing and moisture-retention properties.The optimized GPC hydrogel exhibited a high tensile strength of 1.02 MPa,conductivity of 1.5 S·m^(-1),and stable performance at temperatures down to-50℃.Furthermore,it was successfully assembled into a wearable strain sensor for real-time human motion monitoring,and as an electrode layer in a flexible triboelectric nanogenerator(TENG),enabling biomechanical energy harvesting and self-powered sensing.This work provides a promising strategy for developing sustainable,multifu nctional hydrogels for next-generation weara ble electronics.
基金financially supported by the National Natural Science Foundation of China(Nos.52250398,52125205 and U20A20166)the Natural Science Foundation of Beijing Municipality(No.2222088)+1 种基金Shenzhen Science and Technology Program(No.KQTD20170810105439418)the Fundamental Research Funds for the Central Universities
文摘Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensing ability are urgently required for the precise measurement of large and high-frequency dynamic deformations.However,the existing hysteresis of the current functional materials utilized in strain sensors significantly impedes the achievement of these properties.Herein,we introduce an ultralow dynamic hysteresis capacitive strain sensor using a low-hysteresis and high-relative-permittivity ionic liquid-elastomer composite as the dielectric material.Based on the low-hysteresis dielectric,the prepared capacitive strain sensors exhibit ultralow electrical hysteresis(2.20%at a strain rate of 100% s^(-1)and strain of100%)and maintain low electrical hysteresis(4.35%)even under extremely high strain rates and large dynamic strain loads(a strain rate of 500% s^(-1)and strain of 100%).Moreover,the strain sensor manifests exceptional cyclic stability under 50,000 cycles of 100%strain at a strain rate of 200% s^(-1);the response curves remain nearly identical throughout these 50,000 cycles.Furthermore,the ultralowhysteresis strain sensor was successfully applied to accurate and reliable real-time human-machine interactions,revealing its great potential in various fields,including electronic skin,flexible robotics,wearable electronics,and virtual reality.
基金supported by the National Natural Science Foundation of China(Nos.22301037, 22401045)the Natural Science Foundation of Guangdong Province(No.2022A1515110867).
文摘Eutectogels are considered to have immense application potential in the field of flexible wearable ionotronic devices because of their excellent ionic conductivity,thermal and electrochemical stability,and non-volatility.However,most existing technologies still struggle to achieve synergistic optimization of key performance indicators,such as high mechanical strength and ionic conductivity.To address this chal-lenge,this study successfully prepared a green eutectogel material with outstanding comprehensive properties by leveraging the high solubility of glycerol in a polymerizable deep eutectic solvent(DES)composed of acrylic acid and choline chloride.The resulting eutectogels exhibited a high transparency(89%),high mechanical strength(up to 2.8 MPa),and exceptional tensile performance(up to 1385%).The fabricated flexible sensor demonstrated ideal linear sensitivity(gauge factor:0.88),a broad response range(1%-100%),and reliable stability(over 1000 cycles),en-abling the precise monitoring of human motion(e.g.,finger bending and wrist rotation).The flexible strain sensor based on this eutectogel is ex-pected to show promising prospects for medical monitoring,human-machine interaction,and industrial sensing applications.
基金supported by the National Key Re-search and Development Program of China(No.2021YFA0715700)the National Natural Science Foundation of China(No.52003212).
文摘As a natural biopolymer material,silk fibroin with unique mechanical properties can be used in the preparation of biocomposite hydrogels for strain sensors.But,the electromechanical properties of bio-composite hydrogel strain sensors are still insufficient,such as the deterioration of electrical signals and low sensitivity,which need to develop a hydrogel with a stable transmission network for electric con-duction.Herein,a silk fibroin biocomposite hydrogel is prepared by incorporating tannic acid and MXene nanosheets into a polyacrylamide and silk fibroin double network.The electromechanical properties of hydrogels are improved by optimizing the proportion of material components.As a result,the double network structure and supramolecular interaction enhance the stretchability of hydrogels(692% fracture strain).The hydrogel also exhibits good biocompatibility and conductivity(0.85 S/m),which shows the application prospect in wearable sensors.The wireless strain sensor assembled by this biocomposite hy-drogel presents good portability and sensing performance,such as high sensitivity(gauge factor=6.04),wide working range(500% strain),and outstanding stability(1000 cycles at 100%strain).The results in-dicate that the hydrogel strain sensor can be used to monitor human body movement.The biocomposite hydrogel is expected to be applied in the field of wearable strain sensors,and this study can provide a new way for the design of flexible electronic materials.
基金supported by the National Natural Science Foundation of China(No,22271074)Natural Science Foundation of Hebei Province(Nos.B2023208042,B2022208032,B2021208066,E2024208084 , 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Flexible wearable electronic devices based on hydrogels have immense potential in a wide range of applications.However,many existing strain sensors suffer from significant limitations including poor mechanical properties,low adhesion,and insufficient conductivity.To address these challenges,this study successfully developed an organic-inorganic double-network conductive hydrogel using acrylic-modified bentonite (AABT) as a key component.The incorporation of AABT significantly enhanced the mechanical properties of the ATHG@LiCl hydrogel,achieving an impressive stretchability of 4000% and tensile strength of 250 kPa.Moreover,it improved the electrical conductivity of the hydrogel to a maximum of 1.53 mS/cm.The catechol structure of tannic acid (TA) further augmented the adhesive properties of the ATHG@LiCl hydrogel toward various substrates such as copper,iron,glass,plastic,wood,and pigskin.The addition of lithium chloride (LiCl) and dimethyl sulfoxide(DMSO) endowed the hydrogel with exceptional freezing resistance and flexibility,even at low temperatures of-20℃.Remarkably,the hydrogel maintained a conductivity of 0.53 mS/cm under these conditions,surpassing the performance of many other reported hydrogels.Furthermore,the ATHG@LiCl hydrogel demonstrated outstanding characteristics,such as high sensitivity (gauge factor GF=4.50),excellent transparency (90%),and reliable strain-sensing capabilities,indicating that the ATHG@LiCl hydrogel is a highly promising candidate for flexible wearable soft materials,offering significant advancements in both functionality and performance.
基金supported primarily by National Key Research and Development Program of China(2020YFA0710303)The authors thank the support from Natural Science Foundation of Fujian Province(2024J01258)Scientific Research Foundation of Fuzhou University(510936).
文摘Hydrogels possess significant potential for the development of multifunctional soft materials in smart sensors and wearable devices,attributed to their distinctive properties of softness,conductivity,and biocompatibility.Nevertheless,their widespread application is frequently limited by inadequate mechanical strength and strain capacity.This study introduces a meticulously engineered hydrogel system,LM/SA/P(AAM-co-BMA),which integrates eutectic gallium-indium alloy(EGaIn)as both a polymerization initiator and a flexible filler.The resultant hydrogel demonstrates remarkable tensile strain capabilities of up to 2800% and a tensile strength of 2.3 MPa,achieved through a synergistic interplay of ionic coordination,hydrogen bonding,and physical polymer interactions.Furthermore,the hydrogel exhibits outstanding biocompatibility,recyclability,and stable long-term storage,rendering it an ideal candidate for the continuous monitoring of high-intensity physical activities.
基金the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(No.GZKF-202219)the Belt and Road Joint Laboratory on Measurement and Control Technology(No.MCT202306)。
文摘The fexible strain sensor has found widespread application due to its excellent fexibility,extensibility,and adaptability to various scenarios.This type of sensors face challenges in direction identification owing to strong coupling between the principal strain and transverse resistance.In this study,a silver nanowires(Ag-NWs)/polydimethylsiloxane(PDMS)strain sensor was developed,using a filtration method for preparing the AgNWs film which was then combined with PDMS to create a unidirectional,highly sensitive,fast-responsive,and linear fexible strain sensor.When the grid width is 0.25 mm,the AgNWs/PDMS strain sensor demonstrates an outstanding unidirectional sensitivity,with a strain response solely along the parallel direction of the grid lines(noise ratioα≈8%),and a fast reaction time of roughly 106.99 ms.In the end,this sensor's ability to detect curvature was also demonstrated through LEDs,demonstrating its potential applications in various fields,including automotive,medical,and wearable devices.
基金the National Key Research and Development Program of China(Grant No.2021YFB2012100)the Major Science and Technology Projects in Fujian Province(Grant No.2023HZ021005)+1 种基金the Open Project Program of Fujian Key Laboratory of Special Intelligent Equipment Measurement and Control(Grant No.FJIES2023KF06)the Industry-University-Research Co-operation Fund of the Eighth Research Institute of China Aerospace Science and Technology Corporation(Grant No.SAST2023-061).
文摘High-temperature thin-film strain sensors are advanced technological devices for monitoring stress and strain in extreme environments,but the coupling of temperature and strain at high temperature is a challenge for their use.Here,this issue is addressed by creating a composite ink that combines Pb_(2)Ru_(2)O_(6) and TiB_(2) using polysilazane(PSZ)as a binder.After direct writing and annealing the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film at 800℃ in air,the resulting thin film exhibits a low temperature coefficient of resistance(TCR)of only 281 ppm/℃ over a wide temperature range from 100℃ to 700℃,while also demonstrating high sensitivity with a gauge factor approaching 19.8.This exceptional performance is attributed to the intrinsic properties of Pb_(2)Ru_(2)O_(6),which has positive TCR at high temperature,and TiB2,which has negative TCR at high temperature.Combining these materials reduces the overall TCR of the film.Tests showed that the PSZ/Pb_(2)Ru_(2)O_(6)/TiB_(2) film maintains stable strain responses and significant signal output even under varying temperature.These findings provide valuable insights for developing high-temperature strain sensors with low TCR and high sensitivity,highlighting their potential for applications in high-temperature strain measurements.
文摘The distributed strain sensor has significant application in real time measurement of strain status for large and important engineering structures such as aircraft, bridge and dam. In this paper, a quasi distributed optical fiber strain sensor system is set up using optical time domain reflect technique. The local strain sensors based on a novel microbend configuration are designed and applied to measure local strains along the optical fiber. As the result of the experimental research, the microbend sensors show high sensitivity, good linearity and repeatability in certain operation range.
文摘In recently years,high-performance wearable strain sensors have attracted great attention in academic and industrial.Herein,a conductive polymer composite of electrospun thermoplastic polyurethane(TPU)fibrous film matrix-embedded carbon black(CB)particles with adjustable scaffold network was fabricated for high-sensitive strain sensor.This work indicated the influence of stereoscopic scaffold network structure built under various rotating speeds of collection device in electrospinning process on the electrical response of TPU/CB strain sensor.This structure makes the sensor exhibit combined characters of high sensitivity under stretching strain(gauge factor of 8962.7 at 155%strain),fast response time(60 ms),outstanding stability and durability(>10,000 cycles)and a widely workable stretching range(0–160%).This high-performance,wearable,flexible strain sensor has a broad vision of application such as intelligent terminals,electrical skins,voice measurement and human motion monitoring.Moreover,a theoretical approach was used to analyze mechanical property and a model based on tunneling theory was modified to describe the relative change of resistance upon the applied strain.Meanwhile,two equations based from this model were first proposed and offered an effective but simple approach to analyze the change of number of conductive paths and distance of adjacent conductive particles.
基金supported by the EU Horizon 2020 through project ETEXWELD-H2020-MSCA-RISE-2014(Grant No.644268)The University of Manchester through UMRI project“Graphene-Smart Textiles E-Healthcare Network”(AA14512)National Natural Science Foundation of China(No.22075046).
文摘Wearable strain sensors are arousing increasing research interests in recent years on account of their potentials in motion detection,personal and public healthcare,future entertainment,man-machine interaction,artificial intelligence,and so forth.Much research has focused on fiber-based sensors due to the appealing performance of fibers,including processing flexibility,wearing comfortability,outstanding lifetime and serviceability,low-cost and large-scale capacity.Herein,we review the latest advances in functionalization and device fabrication of fiber materials toward applications in fiber-based wearable strain sensors.We describe the approaches for preparing conductive fibers such as spinning,surface modification,and structural transformation.We also introduce the fabrication and sensing mechanisms of state-of-the-art sensors and analyze their merits and demerits.The applications toward motion detection,healthcare,man-machine interaction,future entertainment,and multifunctional sensing are summarized with typical examples.We finally critically analyze tough challenges and future remarks of fiber-based strain sensors,aiming to implement them in real applications.
基金This project was financially supported by the Research Grants Council(GRF Projects:16229216,16209917,16205517)the Innovation and Technology Commission(ITS/012/19)of Hong Kong SAR.
文摘Flexible multidirectional strain sensors are crucial to accurately determining the complex strain states involved in emerging sensing applications.Although considerable efforts have been made to construct anisotropic structures for improved selective sensing capabilities,existing anisotropic sensors suffer from a trade-off between high sensitivity and high stretchability with acceptable linearity.Here,an ultrasensitive,highly selective multidirectional sensor is developed by rational design of functionally different anisotropic layers.The bilayer sensor consists of an aligned carbon nanotube(CNT)array assembled on top of a periodically wrinkled and cracked CNT-graphene oxide film.The transversely aligned CNT layer bridge the underlying longitudinal microcracks to effectively discourage their propagation even when highly stretched,leading to superior sensitivity with a gauge factor of 287.6 across a broad linear working range of up to 100%strain.The wrinkles generated through a pre-straining/releasing routine in the direction transverse to CNT alignment is responsible for exceptional selectivity of 6.3,to the benefit of accurate detection of loading directions by the multidirectional sensor.This work proposes a unique approach to leveraging the inherent merits of two cross-influential anisotropic structures to resolve the trade-off among sensitivity,selectivity,and stretchability,demonstrating promising applications in full-range,multi-axis human motion detection for wearable electronics and smart robotics.
基金We are grateful for financial supports from the National Natural Science Foundation of China(No.61975173)the National Key Research and Development Program of China(No.SQ2019YFC170311)+3 种基金the Major Scientific Research Project of Zhejiang Lab(No.2019MC0AD01)the Key Research and Development Project of Zhejiang Province(No.2021C05003)the Quantum Joint Funds of the Natural Foundation of Shandong Province(No.ZR2020LLZ007)the CIE-Tencent Robotics X Rhino-Bird Focused Research Program(No.2020-01-006).
文摘Flexible strain sensors play an important role in electronic skins,wearable medical devices,and advanced robots.Herein,a highly sensitive and fast response optical strain sensor with two evanescently coupled optical micro/nanofibers(MNFs)embedded in a polydimethylsiloxane(PDMS)film is proposed.The strain sensor exhibits a gauge factor as high as 64.5 for strain≤0.5%and a strain resolution of 0.0012%which corresponds to elongation of 120 nm on a 1 cm long device.As a proof-of-concept,highly sensitive fingertip pulse measurement is realized.The properties of fast temporal frequency response up to 30 kHz and a pressure sensitivity of 102 kPa^(−1) enable the sensor for sound detection.Such versatile sensor could be of great use in physiological signal monitoring,voice recognition and micro-displacement detection.
基金This work is financed by the National Natural Science Founda-tion of China(No.21978180).We appreciate the valuable help of Dr.Jinwei Zhang from the College of Biomass Science and Engineering of Sichuan University and Hui Wang from the Analytical&Testing Center of Sichuan University.We thank eceshi(www.eceshi.com)for the great help in SEM analysis.
文摘The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydrogel sensors,which can guarantee good accuracy,comfort and long service life.However,it is still a challenge to achieve simultaneous self-healing and self-adhesion in different environments(in the air,underwater and at low temperatures).Herein,a feasible new strategy was successfully carried out to prepare a starch-based composite conductive organohydrogel based on the reversible borate ester bonds formed by complexing starch/polyvinyl alcohol(PVA)/tea polyphenol(TP)with borax,and multiple hydrogen-bond interactions among PVA,starch,TP and ethylene glycol(EG).Silver nanoparticles(Ag-NPs),reduced and stabilized by TP,and MWCNTs(multi-walled carbon nanotubes)were introduced into the cross-linking networks to endow the resulting PBSTCE organohydrogel with considerable antibacterial property and conductivity,respectively.The organohydrogel possessed rapid self-healing(HE(self-healing efficiency)=96.07%in 90 s,both in the air and underwater,also at-20℃),considerable self-adhesion(both in the air and underwater,also at-20℃),remarkable stretchability(814%of elongation),anti-freezing(-20℃)and moisture-retention abilities,antibacterial activity,sensitive pH/sugar-responsiveness,and plasticity.The strain sensor formed by the PBSTCE organohydrogel can not only effectively record large-scale human motions(e.g.finger/wrist/elbow bending,walking,etc.),but also accurately capture subtle motion changes(e.g.breathing,chewing,swallowing,speaking,smiling and frowning).Moreover,the self-healed organohydrogel sensor also exhibited almost invariable mechanical,electrical and sensing behaviors.This work demonstrates a feasible strategy to construct multifunctional starch-based organohy-drogels,and promotes their efficient,stable and eco-friendly application as flexible wearable devices.
基金financially supported by the National Natural Science Foundation of China(No.U1730107)the National Natural Science Foundation of China(No.51522503)+2 种基金the Program for New Century Excellent Talents in University(No.NCET-13-0175)the Natural Sciences and Engineering Research Council(NSERC)of Canada and Canada Research Chairs(CRC)Programsthe China Scholarship Council(CSC)for the graduate fellowship。
文摘We report the direct joining of carbon nanofibers(CNFs)to silver nanowire(Ag NWs)by controlled irradiation with femtosecond(fs)laser pulses.Two separate types of nano-junction dependent on joint geometry,laser fluence and irradiation time are identified in irradiated mixtures.In one type of junction,the tip of an Ag NW is melted and flows to form a bond with an adjacent CNF.The second type of junction occurs without significant heating of the Ag NW and involves the softening and flow of carbon in the CNF in response to the transfer of plasmonic energy from the Ag NW into the CNF.Bonding in a T-type joint configuration can be of either kind depending on the relative orientation of the incident optical field and the long axis of the Ag NW.FDTD simulations were used to explore this effect for different joint geometries and laser polarization.The electrical properties of a heterojunction involving a single Ag NW-CNF structure have been measured,and it is found that the junction resistance can be reduced by six orders of magnitude after laser joining.Finally,we have investigated the properties of a strain sensor based on an Ag NW-CNF hybrid nanowire network and find that this device can exhibit high sensitivity.This sensitivity occurs as nano-junctions induced by fs laser irradiation greatly reduces the initial resistance.This laser-based technique for direct nanojoining of CNF and Ag NWs may enable the design of robust nanowire structures for application in a variety of new devices.
基金The authors thank the Natural Science Funds for Distin-guished Young Scholar of Fujian Province(No.2020J06038)the National Natural Science Foundation of China(Nos.22075046 and 51972063),the Natural Science Foundation of Fujian Province(2019J01256)+1 种基金the start-up funding from Wenzhou Insti-tute,University of Chinese Academy of Sciences(No.WIU-CASQD2019002)Engineering Research Center of Clinical Functional Materials and Diagnosis&Treatment Devices of Zhejiang Province(No.WIBEK181005).
文摘Multifunctional flexible devices for human motion detection and thermal management raised great at-tention as the problem of the aging population is becoming more and more serious.However,it is still a challenge to endow the devices with excellent stability and wide application scope.Here we prepared a hydrophobic and conductive fabric-based strain sensor for smart fabric via successively coating with poly-dopamine(PDA),polyaniline(PANI),polypyrrole(PPy),and polydimethylsiloxane(PDMS)through in-situ polymerization and dip-coating,which could be used for strain sensor and wearable heater both in air and underwater.The obtained sample exhibited a fast electrical response in 500 ms and could withstand 10,000 times stretching-releasing cycles,additionally,the sample exhibited satisfactory electro-thermal and photo-thermal performances.As a whole,the multifunctional fabric-based devices with excellent performances show great potential to be applied in medical monitoring and personal care,especially for aged and disabled persons.
