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
Multifunctional flexible sensors as wearable electronic systems have attracted considerable attention for mimicking human skin to sense ambient stimuli.However,sensors need to have high resolution,stability and sensit...Multifunctional flexible sensors as wearable electronic systems have attracted considerable attention for mimicking human skin to sense ambient stimuli.However,sensors need to have high resolution,stability and sensitivity to realize fully biomimetic skin.Here,an assembled and welded Ag/W composite nanowire flexible electrode was prepared for body motion monitoring and flexible heaters.This Ag/W composite nanowire flexible electrode has a high transmittance of 90.1%(at 121Ω·sq^(−1) sheet resistance)and a low sheet resistance of 27Ω·sq^(−1)(at 60.1%transmittance).Although the transparency of this electrode is not high,the fluctuation in relative resistance change rate at 10%strain is only 5%after 1000 tensile cycles.It can be employed to monitor human body motions,including bending of fingers,arms,wrists,and throat action.Meanwhile,the Ag/W nanowires composite film heater achieves a steady-state temperature of up to 100℃ at a constant voltage of 3.5 V and an instantaneous heating rate of up to 36.5℃·s^(−1).展开更多
Flexible piezoresistive sensors based on biomimetic microstructures are prospective for broad application in motion monitoring.However,the design and preparation processes of most biomimetic microstructures in the exi...Flexible piezoresistive sensors based on biomimetic microstructures are prospective for broad application in motion monitoring.However,the design and preparation processes of most biomimetic microstructures in the existing studies are complicated,and there are few studies on pore size control.Herein,the porous structure of human bones was used as a biomimetic prototype,and optimally designed by creating a theoretical equivalent sensor model and a finite element model.Soluble raw materials such as sugar and salt in different particle sizes were pressed into porous templates.Based on the template method,porous structures in different pore sizes were prepared using polydimethylsiloxane(PDMS)polymer as the substrate.On this basis,graphene oxide conductive coating was prepared with the modified Hummers method and then deposited via dip coating onto the substrate.Finally,a PDMS-based porous structure biomimetic flexible piezoresistive sensor was developed.Mechanically,the deformation of the sensor under the same load increased with the pore size rising from 0.3 to 1.5 mm.Electrically,the resistance rang of the sensor was enlarged as the pore size rose.The resistance variation rates of samples with pore sizes of 0.3,1.0,and 1.5 mm at approximately the 200th cycle were 63%,79%,and 81%,respectively;at the 500th cycle,these values were 63%,77%,and 79%;and at the 1000th cycle,they stabilized at 63%,74%,and 76%.These results indicate that the fabricated sensor exhibits high stability and fatigue resistance.At the pressure of 0–25 kPa,the sensitivity rose from 0.0688 to 0.1260 kPa−1,and the performance was enhanced by 83%.After 1,000 cycles of compression testing,the signal output was stable,and no damage was caused to the substrate.Further application tests showed the biomimetic sensor accurately and effectively identified human joint motions and gestures,and has potential application value in human motion monitoring.展开更多
Wearable devices have great application potential in the next generation of smart portable electronics,especially in the fields of medical monitoring,soft robotics,artificial intelligence,and human-machine interfaces....Wearable devices have great application potential in the next generation of smart portable electronics,especially in the fields of medical monitoring,soft robotics,artificial intelligence,and human-machine interfaces.Piezoelectric flexible strain sensors are key components of wearable devices.However,existing piezoelectric flexible strain sensors have certain limitations in weak signal monitoring due to their large modulus and low sensitivity.To solve this problem,the concept of Kirigami(paper-cutting)was introduced in this study to design the sensor structure.By comparing the Kirigami structures of different basic structures,the serpentine structure was determined as the basic configuration of the sensor.The serpentine structure not only provides excellent tensile properties,but also significantly improves the sensitivity of the sensor,which performs well in monitoring weak signals.On this basis,the adhesion properties of the flexible sensor were analyzed and tested,and the optimal ratio of the substrate was selected for preparation.In addition,a low-cost and rapid prototyping process for stretchable patches was established in this study.Using this technology,we prepared the sensor device and tested its performance.Finally,we successfully developed a flexible sensor with a sensitivity of 0.128 mV/μɛand verified its feasibility for wrist joint motion monitoring applications.This result opens up new avenues for the recovery care of tenosynovitis patients after surgery.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
Piezoresistive pressure sensors have received considerable attention because of their simple structure,high sensitivity and low cost.Graphene,which is known for its outstanding mechanical and electrical properties,has...Piezoresistive pressure sensors have received considerable attention because of their simple structure,high sensitivity and low cost.Graphene,which is known for its outstanding mechanical and electrical properties,has shown great application potential as a sensor material.However,its durability and performance consistency in practical applications still require enhancement.In this study,magnetic graphene fibers(MGFs)are prepared via wet spinning,using graphene oxide(GO),doped with Fe_(3)O_(4)nanoparticles.The resulting MGFs exhibit a high tensile strength of 58.6 MPa,a strain of 5.3%and an electrical conductivity of 1.7×10^(4)S/m.These MGFs are utilised to construct a multilayer fabric for fabrication of flexible pressure sensors.The confinement within the spinning channel facilitates an ordered arrangement of GO sheets,resulting in MGFs with superior electrical and mechanical properties.The issuing MGFs pressure sensors demonstrate a wide detection range(0-120 kPa),high sensitivity(0.233 kPa^(−1),0-40 kPa)and rapid response/recovery times(121 ms/158 ms).In addition,it exhibits a remarkable durability,maintaining performance over 1300 cycles,during continuous operation,with negligible degradation.This sensor shows excellent capability in monitoring human physiological activities,indicating its substantial application potential in wearable devices.展开更多
Quantitative analysis of gait parameters,such as stride frequency and step speed,is essential for optimizing physical exercise for the human body.However,the current electronic sensors used in human motion monitoring ...Quantitative analysis of gait parameters,such as stride frequency and step speed,is essential for optimizing physical exercise for the human body.However,the current electronic sensors used in human motion monitoring remain constrained by factors such as battery life and accuracy.This study developed a self-powered gait analysis system(SGAS)based on a triboelectric nanogenerator(TENG)fabricated electrospun composite nanofibers for motion monitoring and gait analysis for regulating exercise programs.The SGAS consists of a sensing module,a charging module,a data acquisition and processing module,and an Internet of Things(IoT)platform.Within the sensing module,two specialized sensing units,TENG-S1 and TENG-S2,are positioned at the forefoot and heel to generate synchronized signals in tandem with the user's footsteps.These signals are instrumental for real-time step count and step speed monitoring.The output of the two TENG units is significantly improved by systematically investigating and optimizing the electrospun composite nanofibers'composition,strength,and wear resistance.Additionally,a charge amplifier circuit is implemented to process the raw voltage signal,consequently bolstering the reliability of the sensing signal.This refined data is then ready for further reading and calculation by the micro-controller unit(MCU)during the signal transmission process.Finally,the well-conditioned signals are wirelessly transmitted to the IoT platform for data analysis,storage,and visualization,enhancing human motion monitoring.展开更多
Highly sensitive sensors with extensive applications are extremely desired in the next-generation wearable electronics for human motion monitoring,human-machine interface and intelligent robotics,while singlefunctiona...Highly sensitive sensors with extensive applications are extremely desired in the next-generation wearable electronics for human motion monitoring,human-machine interface and intelligent robotics,while singlefunctional pressure sensors cannot fulfill the growing demands of modern technological advances.Herein,an all-fabric and multilayered piezoresistive sensor based on conductive metal-organic frame-work/layered double hydroxide(cMOF/LDH)hetero-nanoforest is demonstrated to achieve multiple applications including pulse detection,joint motion detection,sound detection and information transmission.Benefiting from the synergism of cMOF/LDH hetero-nanoforest and multilayered structure,the sensor exhibits a high sensitivity(1.61×10^(9)kPa^(−1))over a broad pressure range(0-100 kPa),a fast response/recovery time(71 ms/71 ms)and a low detection limit(18 Pa),as well as reliable dynamic stability(8000 cycles).It is gratifying to note that the introduction of cMOFs endows the sensor with the potential to detect the concentration of NH_(3)(1-100 ppm)and sunlight intensity(10-100 mW cm^(−2)).This work shows great potential in multifunctional sensing,which enlightens a strategy for advancing the development process of highly sensitive intelligent wearable devices.展开更多
Strain sensors with high stretchability, broad strain range, high sensitivity, and good reliability are desirable, owing to their promising applications in electronic skins and human motion monitoring systems. In this...Strain sensors with high stretchability, broad strain range, high sensitivity, and good reliability are desirable, owing to their promising applications in electronic skins and human motion monitoring systems. In this paper, we report a high- performance strain sensor based on printable and stretchable electrically con- ductive elastic composites. This strain sensor is fabricated by mixing silver-coated polystyrene spheres （PS@Ag） and liquid polydimethylsiloxane （PDMS） and screen-printed to a desirable geometry. The strain sensor exhibits fascinating comprehensive performances, including high electrical conductivity （1.65 × 104 S/m）, large workable strain range （〉 80%）, high sensitivity （gauge factor of 17.5 in strain of 0%-10%, 6.0 in strain of 10%-60% and 78.6 in strain of 60%-80%）, inconspicuous resistance overshoot （〈 15%）, good reproducibility and excellent long-term stability （1,750 h at 85℃/85% relative humidity） for PS@Ag/PDMS-60, which only contains - 36.7 wt.% of silver. Simultaneously, this strain sensor provides the advantages of low-cost, simple, and large-area scalable fabrication, as well as robust mechanical properties and versatility in applications. Based on these performance characteristics, its applications in flexible printed electrodes and monitoring vigorous human motions are demonstrated, revealing its tremendous potential for applications in flexible and wearable electronics.展开更多
Triboelectric nanogenerators(TENGs)have recently drawn much attention in the field of biomechanical energy harvesting and motion monitoring.However,the electrode stretchability and contact-separation model induced com...Triboelectric nanogenerators(TENGs)have recently drawn much attention in the field of biomechanical energy harvesting and motion monitoring.However,the electrode stretchability and contact-separation model induced complicated packed structure remain a problem that heavily affects output performance during various human movements and requires to be urgently addressed.Here,a single-electrode piezotriboelectric hybrid nanogenerator(SEP-TENG)integrated with stretchable liquid-metal metal electrodes is reported,which simultaneously achieves outstanding energy harvesting performance and skincomfort human motion monitoring.A polarized piezoelectric BaTiO_(3)/silicon rubber(SR)composites film is served as the effective negative tribomaterial,benefiting from the improved dielectric constant and piezoelectric charge transfer,the optimized SEP-TENG generates a high peak power density of 5.7 W/m^(2) while contacted with human skin.Besides,owing to the ultralow Young's modulus of the SR encapsulation layer and tribo-piezoelectric hybrid layer,the homogeneous integrated multilayer composite serves no break till a 745%elongation,promoting that the SEP-TENG could effectively harvest biomechanical energy and realize stable power supplying for wearable electronics even under large deformation state.Furthermore,the SEP-TENG could comfortably attach to the finger joints and collect bending energy.This work provides a novel design methodology for a single-electrode TENG to realize omnidirectional biomechanical energy harvesting and motion monitoring.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
Yarn-based flexible strain sensors with advantages in wearability and integrability have attracted wide at-tention.However,it is still a big challenge to achieve yarn-based strain sensors with a wide linear strain ran...Yarn-based flexible strain sensors with advantages in wearability and integrability have attracted wide at-tention.However,it is still a big challenge to achieve yarn-based strain sensors with a wide linear strain range,low hysteresis,and durability synchronously that can be used for full range detection of human body motions.Herein,a new structure,double-threaded conductive yarn with rhythmic strain distribu-tion,is reported to markedly widen the linear strain range of microcrack-based stretchable strain sensors.A new method of winding and thermally adhering hot-melt filaments on the surface of the elastic fiber is used to achieve double-threaded yarn(DTY)with rhythmic strain distribution.The proposed strategy,the integration of heterogeneous materials,is reported to significantly reduce the mechanical hysteresis of composite yarns.Rhythmic strain distribution of the DTY during stretching causes multi-level micro-cracks in different regions of the carbon nanotube(CNT)conductive layer deposited on the surface of the DTY.Besides,the sensing performance of DTY-based strain sensor can be adjusted by designing the structural parameters.The final prepared flexible strain sensor has the advantages of a wide linear strain range(100%),great sensitivity(GF=12.43),low hysteresis,rapid response(158 ms),high repeatability(>2000 cycles at 50%strain),and hydrophobicity,etc.The sensor can monitor human motion repeatedly and stably well,and shows great advantages in flexible wearable devices.展开更多
Triboelectric nanogenerator(TENG)has been proved as a promising energy harvester in recent years,but the challenges of exploring economically triboelectric materials still exist and have aroused interests of many rese...Triboelectric nanogenerator(TENG)has been proved as a promising energy harvester in recent years,but the challenges of exploring economically triboelectric materials still exist and have aroused interests of many researchers.In this paper,chitosan-silk fibroin-airlaid paper composite film(CSA film)was fabricated and then the CSA film based-triboelectric nanogenerator(CSA-TENG)was constructed,which presents an opportunity for natural polymers to be applied in triboelectric materials.Due to the excellent electron donating ability of CSA film,the CSA-TENG can harvest environmental energy with a high efficiency.More importantly,the as-designed CSA film based dual-electrode triboelectric nanogenerator(CSA-D-TENG)is successfully assembled into hand clapper and trampoline to harvest mechanical energies generated by human bodies,it is also capable of monitoring human movement while harvesting biomechanical energies.This work provides a simple and environmental-friendly way to develop TENG for biomechanical energies harvesting and human motion monitoring.展开更多
Flexible and wearable strain sensors for human-computer interaction,health monitoring,and soft robotics have drawn widespread attention to promising applications in the next generation of artificial intelligence devic...Flexible and wearable strain sensors for human-computer interaction,health monitoring,and soft robotics have drawn widespread attention to promising applications in the next generation of artificial intelligence devices.However,conventional semiconductor sensors are difficult to meet the requirements of flexibility and stretchability.Here,we reported a kind of novel and simple sensor based on layer-by-layer(LBL)method.Carbon nanotubes(CNTs)layer provides high ductility and stability in the process of tension sensing,while silver layer provides low initial resistance and fast reflecting in the process of tension sensing.LBL method ensures the uniformity of the conductive layer.The sensor has superior sheet resistance of 9.44Ω/sq.,high elongation at break of 104%.For sensing capability,the sensor has wide reflecting range of 60%,high gauge factor(GF)of 1000 up to 60%strain,fast reflecting time of 165 ms.Excellent reliability and stability have also been verified.It is also worth mentioning that the entire process does not require any expensive equipments,complicated processes or harsh experimental conditions.The above features provide an idea for large-scale application of flexible stretchable sensors.展开更多
Although there has been rapid advancement in piezoelectric sensors,challenges still remain in developing wearable piezoelectric sensors by a one-step,continuous and environmentally friendly method.In this work,a 1D fl...Although there has been rapid advancement in piezoelectric sensors,challenges still remain in developing wearable piezoelectric sensors by a one-step,continuous and environmentally friendly method.In this work,a 1D flexible coaxial piezoelectric fiber was directly fabricated by melt extrusion molding,whose core and sheath layer are respectively slender steel wire(i.e.,electrode)and PVDF(i.e.,piezoelectric layer).Moreover,such 1D flexible coaxial piezoelectric fiber possesses short response time and high sensitivity,which can be used as a selfpowered sensor for bending and vibration sensing.More interestingly,such 1D flexible coaxial piezoelectric fiber(1D-PFs)can be further endowed with 3D helical structure.Moreover,a wearable and washable motion monitoring system can be constructed via braiding such 3D helical piezoelectric fiber(3D-PF)into commercial textiles.This work paves a new way for developing 1D and 3D piezoelectric fibers through a one-step,continuous and environmentally friendly method,showing potential applications in the field of sensing and wearable electronics.展开更多
Advanced soft ion-conducting hydrogels have been developed rapidly in the integrated portable health monitoring equipment due to their higher sensitivity,sensory traits,tunable conductivity,and stretchability for phys...Advanced soft ion-conducting hydrogels have been developed rapidly in the integrated portable health monitoring equipment due to their higher sensitivity,sensory traits,tunable conductivity,and stretchability for physiological activities and personal healthcare detection.However,traditional hydrogel conductors are normally susceptible to large deformation and strong mechanical stress,which leads to inferior electro-mechanical stability for real application scenarios.Herein,a strong ionically conductive hydrogel(poly(vinyl alcohol)-boric acid-glycerol/sodium alginate-calcium chloride/electrolyte ions(PBG/SC/EI))was designed by engineering the covalently and ionically crosslinked networks followed by the salting-out effect to further enhance the mechanical strength and ionic conductivity of the hydrogel.Owing to the collective effects of the energy-dissipation mechanism and salting-out effect,the designed PBG/SC/EI with excellent structural integrity and robustness exhibits exceptional mechanical properties(elongation at break for 559.1%and tensile strength of 869.4 kPa)and high ionic conductivity(1.618 S·m^(-1)).As such,the PBG/SC/EI strain sensor features high sensitivity(gauge factor=2.29),which can effectively monitor various kinds of human motions(joint motions,facial micro-expression,faint respiration,and voice recognition).Meanwhile,the hydrogel-based Zn||MnO_(2)battery delivers a high capacity of 267.2 mAh·g^(-1)and a maximal energy density of 356.8 Wh·kg^(-1)associated with good cycle performance of 71.8%capacity retention after 8000 cycles.Additionally,an integrated bio-monitoring system with the sensor and Zn||MnO_(2)battery can accurately identify diverse physiological activities in a real-time and non-invasive way.This work presents a feasible strategy for designing high-performance conductive hydrogels for highly-reliable integrated bio-monitoring systems with excellent practicability.展开更多
Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical...Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical applications,such as the damage caused by external effects,leading to equipment failure,and the inability to perceive ambient temperature,resulting in single functionality.Herein,a stretchable,self-healing and dual temperature-strain sensitive hydrogel,with a physically-crosslinked network,is designed by constructing multiple dynamic reversible bonds.Graphene oxide(GO)and iron ions(Fe^(3+))act as dynamic bridges in the cross-linked network and are mediated by the covalent and hydrogen bonding,rendering excellent stretchability to the hydrogel.The reversible features of coordination interactions and hydrogen interactions endow excellent recoverability and self-healing properties.Moreover,the incorporated N-isopropyl acrylamide(NIPAM)provides excellent temperature responsiveness to the hydrogel,facilitating the detection of external temperature changes.Meanwhile,the hydrogels exhibited strain-sensitivity,with a wide working range of 1%-300%,fast response and electrical stability,which can be used as flexible sensors to monitor body motions,e.g.,speaking and the bending of finger,wrist,elbow and knee.Overall,the hydrogel possesses dual sensory capabilities,combining external temperature and strain,for potential applications in wearable multifunctional sensing devices.展开更多
Liquid metals(LMs)are potential inorganic materials which could be applied in flexible and deformable electronics owing to their fluidity,low viscosity,high metallic conductivity,and low toxicity.However,recently repo...Liquid metals(LMs)are potential inorganic materials which could be applied in flexible and deformable electronics owing to their fluidity,low viscosity,high metallic conductivity,and low toxicity.However,recently reported sensing devices based on LMs required complex processes with high cost.Herein,a flexible three-dimensional(3 D)conductive network was prepared by coating LM droplets onto an electrospun thermoplastic polyurethane(TPU)fiber film.The LM is suspended between the TPU fibers and self-coalesces into a vertically buckled and laterally mesh-like structure,which provides good biocompatibility,conductivity,and stretchability simultaneously.The LM-TPU composite-filmbased flexible device demonstrates a multitude of desired features,such as a widely workable stretching range(0%-200%),sufficient sensitivity under stretching strain(gauge factor(GF)of 0.2 at 200%strain),and outstanding stability and durability(9000 cycles).In vitro biocompatibility experiments show that the LM-TPU composite film directly attached to the skin has excellent biocompatibility.Such strain sensorbased integrated monitoring systems could monitor human body motions in real time,such as muscle movement and joint motion,revealing application prospects in healthcare and human-machine interfacing.展开更多
With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human bod...With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human body and high-fidelity collec-tion of biological information remains a significant challenge.Here,a nanoconfinement self-assembly strategy is developed to prepare elastic phenylalanine dipeptide(FF)crystal fibers,in which FF crystals form a unique Mortise-Tenon structure with oriented styrene-block-butadiene-block-styrene molecular beams and thereby obtain elasticity(≈1200%),flexibility(Young’s modulus:0.409±0.031 MPa),piezoelectricity(macroscopic d_(33):10.025±0.33 pC N^(-1)),breathability,and physical stability.Furthermore,elastic FF crystal fibers are used to develop a flexible human physiological movement sensing system by integrating Ga–In alloy coating and wireless electronic transmission components.The system can undergo conformal deformation with human skin and achieve high-fidelity capture of biological information originating from human body motions to prevent diseases(such as Parkinson’s disease).In addition,this system also displays superior sensitivity and accu-racy in detecting subtle pressure changes in vivo during heartbeats,respiration,and diaphragm movement.Therefore,elastic FF crystal fibers hold great potential for developing new flexible electromechanical sensors that are capable of conformal deformation with the human body,enabling precision medical diagnosis and efficient energy harvesting.展开更多
The development of automation industry is inseparable from the progress of sensing technology.As a promising self-powered sensing technology,the durability and stability of triboelectric sensor(TES)have always been in...The development of automation industry is inseparable from the progress of sensing technology.As a promising self-powered sensing technology,the durability and stability of triboelectric sensor(TES)have always been inevitable challenges.Herein,a continuous charge supplement(CCS)strategy and an adaptive signal processing(ASP)method are proposed to improve the lifetime and robustness of TES.The CCS uses low friction brushes to increase the surface charge density of the dielectric,ensuring the reliability of sensing.A triboelectric mechanical motion sensor(TMMS)with CCS is designed,and its electrical signal is hardly attenuated after 1.5 million cycles after reasonable parameter optimization,which is unprecedented in linear TESs.After that,the dynamic characteristics of the CCS-TMMS are analyzed with error rates of less than 1%and 2%for displacement and velocity,respectively,and a signal-to-noise ratio of more than 35 dB.Also,the ASP used a signal conditioning circuit for impedance matching and analog-to-digital conversion to achieve a stable output of digital signals,while the integrated design and manufacture of each hardware module is achieved.Finally,an intelligent logistics transmission system(ILTS)capable of wirelessly monitoring multiple motion parameters is developed.This work is expected to contribute to automation industries such as smart factories and unmanned warehousing.展开更多
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supported by the National Natural Science Foundation of China(Nos.51905103,52275177).
文摘Multifunctional flexible sensors as wearable electronic systems have attracted considerable attention for mimicking human skin to sense ambient stimuli.However,sensors need to have high resolution,stability and sensitivity to realize fully biomimetic skin.Here,an assembled and welded Ag/W composite nanowire flexible electrode was prepared for body motion monitoring and flexible heaters.This Ag/W composite nanowire flexible electrode has a high transmittance of 90.1%(at 121Ω·sq^(−1) sheet resistance)and a low sheet resistance of 27Ω·sq^(−1)(at 60.1%transmittance).Although the transparency of this electrode is not high,the fluctuation in relative resistance change rate at 10%strain is only 5%after 1000 tensile cycles.It can be employed to monitor human body motions,including bending of fingers,arms,wrists,and throat action.Meanwhile,the Ag/W nanowires composite film heater achieves a steady-state temperature of up to 100℃ at a constant voltage of 3.5 V and an instantaneous heating rate of up to 36.5℃·s^(−1).
基金supported by the National Natural Science Foundation of China(52175270)the Project of Scientifc and Technological Development Plan of Jilin Province(20220508130RC)+3 种基金the Science and Technology Development Program of Jilin Province(YDZJ202501ZYTS370)the Scientific Research Project of Education Department of Jilin Province(JJKH20251196KJ)the Scientific Research Project of Education Department of Jilin Province(JJKH20251195KJ)the Key Project of State Key Laboratory of Changchun City(23GZZ14).
文摘Flexible piezoresistive sensors based on biomimetic microstructures are prospective for broad application in motion monitoring.However,the design and preparation processes of most biomimetic microstructures in the existing studies are complicated,and there are few studies on pore size control.Herein,the porous structure of human bones was used as a biomimetic prototype,and optimally designed by creating a theoretical equivalent sensor model and a finite element model.Soluble raw materials such as sugar and salt in different particle sizes were pressed into porous templates.Based on the template method,porous structures in different pore sizes were prepared using polydimethylsiloxane(PDMS)polymer as the substrate.On this basis,graphene oxide conductive coating was prepared with the modified Hummers method and then deposited via dip coating onto the substrate.Finally,a PDMS-based porous structure biomimetic flexible piezoresistive sensor was developed.Mechanically,the deformation of the sensor under the same load increased with the pore size rising from 0.3 to 1.5 mm.Electrically,the resistance rang of the sensor was enlarged as the pore size rose.The resistance variation rates of samples with pore sizes of 0.3,1.0,and 1.5 mm at approximately the 200th cycle were 63%,79%,and 81%,respectively;at the 500th cycle,these values were 63%,77%,and 79%;and at the 1000th cycle,they stabilized at 63%,74%,and 76%.These results indicate that the fabricated sensor exhibits high stability and fatigue resistance.At the pressure of 0–25 kPa,the sensitivity rose from 0.0688 to 0.1260 kPa−1,and the performance was enhanced by 83%.After 1,000 cycles of compression testing,the signal output was stable,and no damage was caused to the substrate.Further application tests showed the biomimetic sensor accurately and effectively identified human joint motions and gestures,and has potential application value in human motion monitoring.
基金supported by National Natural Science Foundation of China(Nos.62301509,62304209)Key Research and Development Program of Shanxi Province(No.202302030201001)Fundamental Research Program of Shanxi Province(Nos.202203021222079,0210302123203,202103021223185).
文摘Wearable devices have great application potential in the next generation of smart portable electronics,especially in the fields of medical monitoring,soft robotics,artificial intelligence,and human-machine interfaces.Piezoelectric flexible strain sensors are key components of wearable devices.However,existing piezoelectric flexible strain sensors have certain limitations in weak signal monitoring due to their large modulus and low sensitivity.To solve this problem,the concept of Kirigami(paper-cutting)was introduced in this study to design the sensor structure.By comparing the Kirigami structures of different basic structures,the serpentine structure was determined as the basic configuration of the sensor.The serpentine structure not only provides excellent tensile properties,but also significantly improves the sensitivity of the sensor,which performs well in monitoring weak signals.On this basis,the adhesion properties of the flexible sensor were analyzed and tested,and the optimal ratio of the substrate was selected for preparation.In addition,a low-cost and rapid prototyping process for stretchable patches was established in this study.Using this technology,we prepared the sensor device and tested its performance.Finally,we successfully developed a flexible sensor with a sensitivity of 0.128 mV/μɛand verified its feasibility for wrist joint motion monitoring applications.This result opens up new avenues for the recovery care of tenosynovitis patients after surgery.
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 Zhejiang Natural Science Foundation Technology Project(LGG22E030015)National Key Research and Development Program of China support by Ministry of Science and Technology(2022YFB3704504)+5 种基金Jiaxing Science and Technology Plan Project(2023AY11004)Jiaxing Project of Science and Technology(2023AY11014)Jiaxing University General Cultivation Project(00321056AL)Qinshen Youth Backbone Training Program of Jiaxing University(CD70623038)Jiaxing City Public Welfare Project(Young Talent Special Project)(2023AY40027)Key Laboratory of Yarn Materials Forming and Composite Processing Technology,Zhejiang Province(MTC-2022-06).
文摘Piezoresistive pressure sensors have received considerable attention because of their simple structure,high sensitivity and low cost.Graphene,which is known for its outstanding mechanical and electrical properties,has shown great application potential as a sensor material.However,its durability and performance consistency in practical applications still require enhancement.In this study,magnetic graphene fibers(MGFs)are prepared via wet spinning,using graphene oxide(GO),doped with Fe_(3)O_(4)nanoparticles.The resulting MGFs exhibit a high tensile strength of 58.6 MPa,a strain of 5.3%and an electrical conductivity of 1.7×10^(4)S/m.These MGFs are utilised to construct a multilayer fabric for fabrication of flexible pressure sensors.The confinement within the spinning channel facilitates an ordered arrangement of GO sheets,resulting in MGFs with superior electrical and mechanical properties.The issuing MGFs pressure sensors demonstrate a wide detection range(0-120 kPa),high sensitivity(0.233 kPa^(−1),0-40 kPa)and rapid response/recovery times(121 ms/158 ms).In addition,it exhibits a remarkable durability,maintaining performance over 1300 cycles,during continuous operation,with negligible degradation.This sensor shows excellent capability in monitoring human physiological activities,indicating its substantial application potential in wearable devices.
基金supported by the National Natural Science Foundation of China(62004083)the Fundamental Research Funds for the Central Universities(21622410)。
文摘Quantitative analysis of gait parameters,such as stride frequency and step speed,is essential for optimizing physical exercise for the human body.However,the current electronic sensors used in human motion monitoring remain constrained by factors such as battery life and accuracy.This study developed a self-powered gait analysis system(SGAS)based on a triboelectric nanogenerator(TENG)fabricated electrospun composite nanofibers for motion monitoring and gait analysis for regulating exercise programs.The SGAS consists of a sensing module,a charging module,a data acquisition and processing module,and an Internet of Things(IoT)platform.Within the sensing module,two specialized sensing units,TENG-S1 and TENG-S2,are positioned at the forefoot and heel to generate synchronized signals in tandem with the user's footsteps.These signals are instrumental for real-time step count and step speed monitoring.The output of the two TENG units is significantly improved by systematically investigating and optimizing the electrospun composite nanofibers'composition,strength,and wear resistance.Additionally,a charge amplifier circuit is implemented to process the raw voltage signal,consequently bolstering the reliability of the sensing signal.This refined data is then ready for further reading and calculation by the micro-controller unit(MCU)during the signal transmission process.Finally,the well-conditioned signals are wirelessly transmitted to the IoT platform for data analysis,storage,and visualization,enhancing human motion monitoring.
基金supported by the National Natural Science Foundation of China(Nos.52271209 and 51762013)the Key Project of Hebei Natural Science Foundation(No.E20202201030)+5 种基金the Beijing-Tianjin-Hebei Collaborative Innovation Community Construction Project(No.21344301D)the Second Batch of Young Talent of Hebei Province(Nos.70280016160250 and 70280011808)the Key Fund in Hebei Province Department of Education China(No.ZD2021014)the Central Government Guide Local Funding Projects for Scientific and Technological Development(Nos.216Z4404G and 206Z4402G)the Interdisciplinary Research Program of Natural Science of Hebei University(No.DXK202107)the Government Foundation of Clinical Medicine Talents Training Program of Hebei Province(No.361007).
文摘Highly sensitive sensors with extensive applications are extremely desired in the next-generation wearable electronics for human motion monitoring,human-machine interface and intelligent robotics,while singlefunctional pressure sensors cannot fulfill the growing demands of modern technological advances.Herein,an all-fabric and multilayered piezoresistive sensor based on conductive metal-organic frame-work/layered double hydroxide(cMOF/LDH)hetero-nanoforest is demonstrated to achieve multiple applications including pulse detection,joint motion detection,sound detection and information transmission.Benefiting from the synergism of cMOF/LDH hetero-nanoforest and multilayered structure,the sensor exhibits a high sensitivity(1.61×10^(9)kPa^(−1))over a broad pressure range(0-100 kPa),a fast response/recovery time(71 ms/71 ms)and a low detection limit(18 Pa),as well as reliable dynamic stability(8000 cycles).It is gratifying to note that the introduction of cMOFs endows the sensor with the potential to detect the concentration of NH_(3)(1-100 ppm)and sunlight intensity(10-100 mW cm^(−2)).This work shows great potential in multifunctional sensing,which enlightens a strategy for advancing the development process of highly sensitive intelligent wearable devices.
基金This work was supported by the National Key R＆D Project from Minister of Science and Technology of China （No. 2016YFA0202702）, National Natural Science Foundation of China （Nos. 61701488 and 21571186）, Leading Scientific Research Project of Chinese Academy of Sciences （No. QYZDY-SSW-JSC010）, Youth Innovation Promotion Association （No. 2017411）, Guangdong Provincial Key Laboratory （No. 2014B030301014）, Guangdong TeZhi Plan Youth Talent of Science and Technology （No. 2014TQ01C102）, Shenzhen Basic Research plan （Nos. JSGG20150512145714246 and JSGG20160229155249762） and SIAT Innovation Program for Excellent Young Researchers （No. 2016005）.
文摘Strain sensors with high stretchability, broad strain range, high sensitivity, and good reliability are desirable, owing to their promising applications in electronic skins and human motion monitoring systems. In this paper, we report a high- performance strain sensor based on printable and stretchable electrically con- ductive elastic composites. This strain sensor is fabricated by mixing silver-coated polystyrene spheres （PS@Ag） and liquid polydimethylsiloxane （PDMS） and screen-printed to a desirable geometry. The strain sensor exhibits fascinating comprehensive performances, including high electrical conductivity （1.65 × 104 S/m）, large workable strain range （〉 80%）, high sensitivity （gauge factor of 17.5 in strain of 0%-10%, 6.0 in strain of 10%-60% and 78.6 in strain of 60%-80%）, inconspicuous resistance overshoot （〈 15%）, good reproducibility and excellent long-term stability （1,750 h at 85℃/85% relative humidity） for PS@Ag/PDMS-60, which only contains - 36.7 wt.% of silver. Simultaneously, this strain sensor provides the advantages of low-cost, simple, and large-area scalable fabrication, as well as robust mechanical properties and versatility in applications. Based on these performance characteristics, its applications in flexible printed electrodes and monitoring vigorous human motions are demonstrated, revealing its tremendous potential for applications in flexible and wearable electronics.
基金This work was supported by the National Key R&D Program of China(grant numbers 2019YFB2004802,2019YFE0120300)National Natural Science Foundation of China(grant numbers 51975542,52175554)+1 种基金National Defense Fundamental Research Project,Shanxi province key laboratory of quantum sensing and precision measurement(grant number 201905D121001)Natural Science Foundation of Shanxi Province(grant numbers 20210302123059,201801D121152).
文摘Triboelectric nanogenerators(TENGs)have recently drawn much attention in the field of biomechanical energy harvesting and motion monitoring.However,the electrode stretchability and contact-separation model induced complicated packed structure remain a problem that heavily affects output performance during various human movements and requires to be urgently addressed.Here,a single-electrode piezotriboelectric hybrid nanogenerator(SEP-TENG)integrated with stretchable liquid-metal metal electrodes is reported,which simultaneously achieves outstanding energy harvesting performance and skincomfort human motion monitoring.A polarized piezoelectric BaTiO_(3)/silicon rubber(SR)composites film is served as the effective negative tribomaterial,benefiting from the improved dielectric constant and piezoelectric charge transfer,the optimized SEP-TENG generates a high peak power density of 5.7 W/m^(2) while contacted with human skin.Besides,owing to the ultralow Young's modulus of the SR encapsulation layer and tribo-piezoelectric hybrid layer,the homogeneous integrated multilayer composite serves no break till a 745%elongation,promoting that the SEP-TENG could effectively harvest biomechanical energy and realize stable power supplying for wearable electronics even under large deformation state.Furthermore,the SEP-TENG could comfortably attach to the finger joints and collect bending energy.This work provides a novel design methodology for a single-electrode TENG to realize omnidirectional biomechanical energy harvesting and motion monitoring.
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supported by the Natural Science Foundation of Shanghai(Nos.20ZR1400500,22ZR1400800)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSF-DH-D-2022043).
文摘Yarn-based flexible strain sensors with advantages in wearability and integrability have attracted wide at-tention.However,it is still a big challenge to achieve yarn-based strain sensors with a wide linear strain range,low hysteresis,and durability synchronously that can be used for full range detection of human body motions.Herein,a new structure,double-threaded conductive yarn with rhythmic strain distribu-tion,is reported to markedly widen the linear strain range of microcrack-based stretchable strain sensors.A new method of winding and thermally adhering hot-melt filaments on the surface of the elastic fiber is used to achieve double-threaded yarn(DTY)with rhythmic strain distribution.The proposed strategy,the integration of heterogeneous materials,is reported to significantly reduce the mechanical hysteresis of composite yarns.Rhythmic strain distribution of the DTY during stretching causes multi-level micro-cracks in different regions of the carbon nanotube(CNT)conductive layer deposited on the surface of the DTY.Besides,the sensing performance of DTY-based strain sensor can be adjusted by designing the structural parameters.The final prepared flexible strain sensor has the advantages of a wide linear strain range(100%),great sensitivity(GF=12.43),low hysteresis,rapid response(158 ms),high repeatability(>2000 cycles at 50%strain),and hydrophobicity,etc.The sensor can monitor human motion repeatedly and stably well,and shows great advantages in flexible wearable devices.
基金the National Key R&D Project from Ministry of Science and Technology(Nos.2016YFA0202702 and 2016YFA0202701)the Key Research Program of Frontier Sciences,CAS(No.ZDBS-LY-DQC025)。
文摘Triboelectric nanogenerator(TENG)has been proved as a promising energy harvester in recent years,but the challenges of exploring economically triboelectric materials still exist and have aroused interests of many researchers.In this paper,chitosan-silk fibroin-airlaid paper composite film(CSA film)was fabricated and then the CSA film based-triboelectric nanogenerator(CSA-TENG)was constructed,which presents an opportunity for natural polymers to be applied in triboelectric materials.Due to the excellent electron donating ability of CSA film,the CSA-TENG can harvest environmental energy with a high efficiency.More importantly,the as-designed CSA film based dual-electrode triboelectric nanogenerator(CSA-D-TENG)is successfully assembled into hand clapper and trampoline to harvest mechanical energies generated by human bodies,it is also capable of monitoring human movement while harvesting biomechanical energies.This work provides a simple and environmental-friendly way to develop TENG for biomechanical energies harvesting and human motion monitoring.
基金financially supported by the National Natural Science Foundation of China(No.51403115)。
文摘Flexible and wearable strain sensors for human-computer interaction,health monitoring,and soft robotics have drawn widespread attention to promising applications in the next generation of artificial intelligence devices.However,conventional semiconductor sensors are difficult to meet the requirements of flexibility and stretchability.Here,we reported a kind of novel and simple sensor based on layer-by-layer(LBL)method.Carbon nanotubes(CNTs)layer provides high ductility and stability in the process of tension sensing,while silver layer provides low initial resistance and fast reflecting in the process of tension sensing.LBL method ensures the uniformity of the conductive layer.The sensor has superior sheet resistance of 9.44Ω/sq.,high elongation at break of 104%.For sensing capability,the sensor has wide reflecting range of 60%,high gauge factor(GF)of 1000 up to 60%strain,fast reflecting time of 165 ms.Excellent reliability and stability have also been verified.It is also worth mentioning that the entire process does not require any expensive equipments,complicated processes or harsh experimental conditions.The above features provide an idea for large-scale application of flexible stretchable sensors.
基金the National Natural Science Foundation of China(No.51873199)Program for Innovative Research Team(in Science and Technology)in University(No.20IRTSTHN002)。
文摘Although there has been rapid advancement in piezoelectric sensors,challenges still remain in developing wearable piezoelectric sensors by a one-step,continuous and environmentally friendly method.In this work,a 1D flexible coaxial piezoelectric fiber was directly fabricated by melt extrusion molding,whose core and sheath layer are respectively slender steel wire(i.e.,electrode)and PVDF(i.e.,piezoelectric layer).Moreover,such 1D flexible coaxial piezoelectric fiber possesses short response time and high sensitivity,which can be used as a selfpowered sensor for bending and vibration sensing.More interestingly,such 1D flexible coaxial piezoelectric fiber(1D-PFs)can be further endowed with 3D helical structure.Moreover,a wearable and washable motion monitoring system can be constructed via braiding such 3D helical piezoelectric fiber(3D-PF)into commercial textiles.This work paves a new way for developing 1D and 3D piezoelectric fibers through a one-step,continuous and environmentally friendly method,showing potential applications in the field of sensing and wearable electronics.
基金support from the National Natural Science Foundation of China(Nos.21965033,U2003216,22269023,and U2003132)the Key Research and Development Task Special Program of Xinjiang Uygur Autonomous Region(No.2022B01040-3)+2 种基金the Special Projects on Regional Collaborative Innovation-SCO Science and Technology Partnership Program,and the International Science and Technology Cooperation Program(Nos.2022E01020 and 2022E01056)Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2022D01C25)gratefully acknowledged.Z.C.W.acknowledges the European Research Executive Agency(Project 101079184-FUNLAYERS).
文摘Advanced soft ion-conducting hydrogels have been developed rapidly in the integrated portable health monitoring equipment due to their higher sensitivity,sensory traits,tunable conductivity,and stretchability for physiological activities and personal healthcare detection.However,traditional hydrogel conductors are normally susceptible to large deformation and strong mechanical stress,which leads to inferior electro-mechanical stability for real application scenarios.Herein,a strong ionically conductive hydrogel(poly(vinyl alcohol)-boric acid-glycerol/sodium alginate-calcium chloride/electrolyte ions(PBG/SC/EI))was designed by engineering the covalently and ionically crosslinked networks followed by the salting-out effect to further enhance the mechanical strength and ionic conductivity of the hydrogel.Owing to the collective effects of the energy-dissipation mechanism and salting-out effect,the designed PBG/SC/EI with excellent structural integrity and robustness exhibits exceptional mechanical properties(elongation at break for 559.1%and tensile strength of 869.4 kPa)and high ionic conductivity(1.618 S·m^(-1)).As such,the PBG/SC/EI strain sensor features high sensitivity(gauge factor=2.29),which can effectively monitor various kinds of human motions(joint motions,facial micro-expression,faint respiration,and voice recognition).Meanwhile,the hydrogel-based Zn||MnO_(2)battery delivers a high capacity of 267.2 mAh·g^(-1)and a maximal energy density of 356.8 Wh·kg^(-1)associated with good cycle performance of 71.8%capacity retention after 8000 cycles.Additionally,an integrated bio-monitoring system with the sensor and Zn||MnO_(2)battery can accurately identify diverse physiological activities in a real-time and non-invasive way.This work presents a feasible strategy for designing high-performance conductive hydrogels for highly-reliable integrated bio-monitoring systems with excellent practicability.
基金financially supported by the National Natural Science Foundation of China(No.52173301)International Science and Technology Cooperation Project of Sichuan Province(No.2022YFH0019)Innovative Research Team of Southwest Petroleum University(No.2017CXTD01)。
文摘Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical applications,such as the damage caused by external effects,leading to equipment failure,and the inability to perceive ambient temperature,resulting in single functionality.Herein,a stretchable,self-healing and dual temperature-strain sensitive hydrogel,with a physically-crosslinked network,is designed by constructing multiple dynamic reversible bonds.Graphene oxide(GO)and iron ions(Fe^(3+))act as dynamic bridges in the cross-linked network and are mediated by the covalent and hydrogen bonding,rendering excellent stretchability to the hydrogel.The reversible features of coordination interactions and hydrogen interactions endow excellent recoverability and self-healing properties.Moreover,the incorporated N-isopropyl acrylamide(NIPAM)provides excellent temperature responsiveness to the hydrogel,facilitating the detection of external temperature changes.Meanwhile,the hydrogels exhibited strain-sensitivity,with a wide working range of 1%-300%,fast response and electrical stability,which can be used as flexible sensors to monitor body motions,e.g.,speaking and the bending of finger,wrist,elbow and knee.Overall,the hydrogel possesses dual sensory capabilities,combining external temperature and strain,for potential applications in wearable multifunctional sensing devices.
基金supported by the National Natural Science Foundation of China(61625404,61888102,and 62174152)Foshan Innovative and Entrepreneurial Research Team Program(2018IT100031)。
文摘Liquid metals(LMs)are potential inorganic materials which could be applied in flexible and deformable electronics owing to their fluidity,low viscosity,high metallic conductivity,and low toxicity.However,recently reported sensing devices based on LMs required complex processes with high cost.Herein,a flexible three-dimensional(3 D)conductive network was prepared by coating LM droplets onto an electrospun thermoplastic polyurethane(TPU)fiber film.The LM is suspended between the TPU fibers and self-coalesces into a vertically buckled and laterally mesh-like structure,which provides good biocompatibility,conductivity,and stretchability simultaneously.The LM-TPU composite-filmbased flexible device demonstrates a multitude of desired features,such as a widely workable stretching range(0%-200%),sufficient sensitivity under stretching strain(gauge factor(GF)of 0.2 at 200%strain),and outstanding stability and durability(9000 cycles).In vitro biocompatibility experiments show that the LM-TPU composite film directly attached to the skin has excellent biocompatibility.Such strain sensorbased integrated monitoring systems could monitor human body motions in real time,such as muscle movement and joint motion,revealing application prospects in healthcare and human-machine interfacing.
基金support from the National Natural Science Foundation of China(82472159,82302406,52303186)China Postdoctoral Science Foundation(2024T171167,2023M731696,2022TQ0158,2022M721616)+1 种基金Jiangsu Funding Program for Excellent Postdoctoral Talent(2023ZB539,2022ZB250)the Fundamental Research Funds for the Central Universities(30923010307,30920041105).
文摘With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human body and high-fidelity collec-tion of biological information remains a significant challenge.Here,a nanoconfinement self-assembly strategy is developed to prepare elastic phenylalanine dipeptide(FF)crystal fibers,in which FF crystals form a unique Mortise-Tenon structure with oriented styrene-block-butadiene-block-styrene molecular beams and thereby obtain elasticity(≈1200%),flexibility(Young’s modulus:0.409±0.031 MPa),piezoelectricity(macroscopic d_(33):10.025±0.33 pC N^(-1)),breathability,and physical stability.Furthermore,elastic FF crystal fibers are used to develop a flexible human physiological movement sensing system by integrating Ga–In alloy coating and wireless electronic transmission components.The system can undergo conformal deformation with human skin and achieve high-fidelity capture of biological information originating from human body motions to prevent diseases(such as Parkinson’s disease).In addition,this system also displays superior sensitivity and accu-racy in detecting subtle pressure changes in vivo during heartbeats,respiration,and diaphragm movement.Therefore,elastic FF crystal fibers hold great potential for developing new flexible electromechanical sensors that are capable of conformal deformation with the human body,enabling precision medical diagnosis and efficient energy harvesting.
基金The authors are grateful for the support received from the National Key R&D Project from the Minister of Science and Technology(Nos.2021YFA1201601 and 2021YFA1201604)the Open Research Project Programme of the State Key Laboratory of Internet of Things for Smart City(University of Macao)(No.SKL-IoTSC(UM)-2021-2023/ORPF/A17/2022).
文摘The development of automation industry is inseparable from the progress of sensing technology.As a promising self-powered sensing technology,the durability and stability of triboelectric sensor(TES)have always been inevitable challenges.Herein,a continuous charge supplement(CCS)strategy and an adaptive signal processing(ASP)method are proposed to improve the lifetime and robustness of TES.The CCS uses low friction brushes to increase the surface charge density of the dielectric,ensuring the reliability of sensing.A triboelectric mechanical motion sensor(TMMS)with CCS is designed,and its electrical signal is hardly attenuated after 1.5 million cycles after reasonable parameter optimization,which is unprecedented in linear TESs.After that,the dynamic characteristics of the CCS-TMMS are analyzed with error rates of less than 1%and 2%for displacement and velocity,respectively,and a signal-to-noise ratio of more than 35 dB.Also,the ASP used a signal conditioning circuit for impedance matching and analog-to-digital conversion to achieve a stable output of digital signals,while the integrated design and manufacture of each hardware module is achieved.Finally,an intelligent logistics transmission system(ILTS)capable of wirelessly monitoring multiple motion parameters is developed.This work is expected to contribute to automation industries such as smart factories and unmanned warehousing.
