Carbon fibre(CF)embedded into elastomeric media has been attracting incredible interest as flexible strain sensors in the application of skin electronics owing to their high sensitivity in a very small strain gauge.To...Carbon fibre(CF)embedded into elastomeric media has been attracting incredible interest as flexible strain sensors in the application of skin electronics owing to their high sensitivity in a very small strain gauge.To further improve the sensitivity of CF/PDMS composite strain sensor,the relatively low temperature prepared TiO_(2) nanowire via hydrothermal route was employed herein to functionalize CF.The results showed a significant increase in the sensitivity of the TiO_(2)@CF/PDMS composite strain sensors which was reflected by the calculated gauge factor.As the prepared TiO_(2) nanowire vertically embraced the surroundings of the CF,the introduced TiO_(2) nanowire contributed to a highly porous structure which played a predominant role in improving the sensitivity of strain sensors.Moreover,the significant strain rate dependent behavior of TiO_(2)@CF/PDMS strain sensor was revealed when performing monotonic tests at varied strain rate.Therefore,introducing TiO_(2) nanowire on CF offers a new technique for fabricating flexible strain sensors with improved sensitivity for the application of flexible electronics.展开更多
Flexible strain sensor has attracted much attention because of its potential application in human motion detection.In this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS...Flexible strain sensor has attracted much attention because of its potential application in human motion detection.In this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS)with room temperature vulcanized silicone rubber(RTVS).In this paper,the formation mechanism of conductive sponge was studied.Based on the combination of carbonized sponge and RTVS,the strain sensing mechanism and piezoresistive properties are discussed.After research and testing,the CS/RTVS flexible strain sensor has excellent fast response speed and stability,and the maximum strain coefficient of the sensor is 136.27.In this study,the self-developed CS/RTVS sensor was used to monitor the movements of the wrist joint,arm elbow joint and fingers in real time.Research experiments show that CS/RTVS flexible strain sensor has good application prospects in the field of human motion monitoring.展开更多
The flexible wearable sensors with excellent stretchability,high sensitivity and good biocompatibility are significantly required for continuously physical condition tracking in health management and rehabilitation mo...The flexible wearable sensors with excellent stretchability,high sensitivity and good biocompatibility are significantly required for continuously physical condition tracking in health management and rehabilitation monitoring.Herein,we present a high-performance wearable sensor.The sensor is prepared with nanocomposite hydrogel by using silk fibroin(SF),polyacrylamide(PAM),polydopamine(PDA)and graphene oxide(GO).It can be used to monitor body motions(including large-scale and small-scale motions)as well as human electrophysiological(ECG)signals with high sensitivity,wide sensing range,and fast response time.Therefore,the proposed sensor is promising in the fields of rehabilitation,motion monitoring and disease diagnosis.展开更多
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
With the rapid development of smart products,fexible and stretchable smart wearable electronic devices gradually play an important role,and they are considered as the pioneers of the new generation of fexible electron...With the rapid development of smart products,fexible and stretchable smart wearable electronic devices gradually play an important role,and they are considered as the pioneers of the new generation of fexible electronic devices.Among these intelligent devices,fexible and stretchable strain sensors have been widely studied for their good fexibility,high sensitivity,high repeatability and huge potential for application in personal healthcare and motion detection.Moreover,unlike traditional rigid bulky sensors,the high-performance fexible strain sensors are lightweight portable devices with excellent mechanical and electrical performance,which can meet personalized needs and become more popular.Herein,the research progress of fexible strain sensors in recent years are reviewed,which mainly introducing the sensing principles and key parameters of strain sensors,commonly used conductive materials and fexible substrates and common preparation methods,and fnally proposes the future application and prospects of strain sensors.展开更多
Flexible sensors for high strain sensitivity and dynamic stability are important for the development of human-interactive and health-monitoring devices.However,establishing a stable conductive network with low-conduct...Flexible sensors for high strain sensitivity and dynamic stability are important for the development of human-interactive and health-monitoring devices.However,establishing a stable conductive network with low-conductivity material filling that can resist tensile strain failure and achieve high device performance still faces significant challenges.Herein,a highly stretchable and sensitive strain sensor with strong dynamic stability and low conductive materials filling was fabricated based on highly conductive multi-walled carbon nanotubes(MWCNTs)and Fe nanowires(NWs)to construct a porous-designed bi-conducting network using a salt sacrificial template approach.The porous-designed Fe NW/MWCNT strain sensor(PFMS)with low material filling(3.6 wt.%Fe NWs and 10.6 wt.%MWCNTs)showed high sensitivity with a gauge factor(GF)of 134.98(strain range 0–22%)and 569.37(strain range 22%–60%),which is much higher compared with the pure MWCNT strain sensor with a GF of 7.46.This is attributed to the significant change in the contact area and contact resistance of the Fe NW/MWCNT bi-conducting network during tensile strain.In addition,the PFMS exhibited high repetitive stability over 2000 stretching-releasing cycles.When attached to the human body,the PFMS functions as a health-monitoring device,that can accurately distinguish human motions such as the bending of fingers,knees,and elbows.Finally,the proposed strategy pens a novel avenue for constructing porous conductive networks using polymer composites and is highly competitive for developing high-performance strain sensors.展开更多
Smart structures have the advantages of high system integrity and diverse sensing capabilities.However,the labor-intensive and timeconsuming fabrication process hinders the large-scale adoption of smart structures.Des...Smart structures have the advantages of high system integrity and diverse sensing capabilities.However,the labor-intensive and timeconsuming fabrication process hinders the large-scale adoption of smart structures.Despite recent attempts to develop sensorembedded structures using 3D printing technologies,the reported smart structures generally suffer from the complex fabrication process,constrained part size,and limited sensing modality.Herein,we propose a workflow to design and fabricate novel smart structures via multi-material fused deposition modeling(FDM)-based 3D printing.More specifically,conductive filaments with tailorable mechanical and elec-trical properties,e.g.piezoresistive effects,were developed.Additionally,the printing process was optimized for processing soft filaments with Young’s modulus around 2 MPa,resolving the issue of filament buckling.Furthermore,the potential applications of the proposed workflow were showcased using three design cases,i.e.biaxial strain sensor,smart tire,and cable-driven soft finger with multiple sensing capabilities.This workflow provides a cost-effective and rapid solution for developing novel smart structures with soft materials.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
基金supported by the Start-Up Funds for Outstanding Talents in Central South University through Project Nos.202045007 and 202044017.
文摘Carbon fibre(CF)embedded into elastomeric media has been attracting incredible interest as flexible strain sensors in the application of skin electronics owing to their high sensitivity in a very small strain gauge.To further improve the sensitivity of CF/PDMS composite strain sensor,the relatively low temperature prepared TiO_(2) nanowire via hydrothermal route was employed herein to functionalize CF.The results showed a significant increase in the sensitivity of the TiO_(2)@CF/PDMS composite strain sensors which was reflected by the calculated gauge factor.As the prepared TiO_(2) nanowire vertically embraced the surroundings of the CF,the introduced TiO_(2) nanowire contributed to a highly porous structure which played a predominant role in improving the sensitivity of strain sensors.Moreover,the significant strain rate dependent behavior of TiO_(2)@CF/PDMS strain sensor was revealed when performing monotonic tests at varied strain rate.Therefore,introducing TiO_(2) nanowire on CF offers a new technique for fabricating flexible strain sensors with improved sensitivity for the application of flexible electronics.
基金This research is supported by the Science and Technology Department of Jilin Province[20210202128NC]The People’s Republic of China Ministry of Science and Technology[2018YFF0213606-03]Jilin Province Development and Reform Commission[2019C021].
文摘Flexible strain sensor has attracted much attention because of its potential application in human motion detection.In this work,the prepared strain sensor was obtained by encapsulating electrospun carbonized sponge(CS)with room temperature vulcanized silicone rubber(RTVS).In this paper,the formation mechanism of conductive sponge was studied.Based on the combination of carbonized sponge and RTVS,the strain sensing mechanism and piezoresistive properties are discussed.After research and testing,the CS/RTVS flexible strain sensor has excellent fast response speed and stability,and the maximum strain coefficient of the sensor is 136.27.In this study,the self-developed CS/RTVS sensor was used to monitor the movements of the wrist joint,arm elbow joint and fingers in real time.Research experiments show that CS/RTVS flexible strain sensor has good application prospects in the field of human motion monitoring.
基金Smart Medicine Research Project of Chongqing Medical University in 2020(YJSZHYX202022)Smart Medicine Research Project of Chongqing Medical University(ZHYX2019019)Chongqing Research Program of Basic Research and Frontier Technology(cstc2018jcyjAX0165).
文摘The flexible wearable sensors with excellent stretchability,high sensitivity and good biocompatibility are significantly required for continuously physical condition tracking in health management and rehabilitation monitoring.Herein,we present a high-performance wearable sensor.The sensor is prepared with nanocomposite hydrogel by using silk fibroin(SF),polyacrylamide(PAM),polydopamine(PDA)and graphene oxide(GO).It can be used to monitor body motions(including large-scale and small-scale motions)as well as human electrophysiological(ECG)signals with high sensitivity,wide sensing range,and fast response time.Therefore,the proposed sensor is promising in the fields of rehabilitation,motion monitoring and disease diagnosis.
基金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Financial support of this work was provided by Natural Science Foundation of Shandong Province of China(ZR2018QEM004,ZR2020QE081)Shandong Province Key Research and Development Plan(Major scientifc and technological innovation projects)(2019JZZY010340,2019JZZY010335,2019GGX102022)China Postdoctoral Science Foundation via grant No.2020M671994.
文摘With the rapid development of smart products,fexible and stretchable smart wearable electronic devices gradually play an important role,and they are considered as the pioneers of the new generation of fexible electronic devices.Among these intelligent devices,fexible and stretchable strain sensors have been widely studied for their good fexibility,high sensitivity,high repeatability and huge potential for application in personal healthcare and motion detection.Moreover,unlike traditional rigid bulky sensors,the high-performance fexible strain sensors are lightweight portable devices with excellent mechanical and electrical performance,which can meet personalized needs and become more popular.Herein,the research progress of fexible strain sensors in recent years are reviewed,which mainly introducing the sensing principles and key parameters of strain sensors,commonly used conductive materials and fexible substrates and common preparation methods,and fnally proposes the future application and prospects of strain sensors.
基金supported by the National Natural Science Foundation of China(Grant No.61901073)the China Postdoctoral Science Foundation funded project(Grant Nos.2021MD703936 and 2022MD713695)+3 种基金the Special Foundation of Chongqing Postdoctoral Research Project(Grant No.2021XM3032)the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202100617)the Innovation Research Group of Universities in Chongqing(Grant No.CXQT20016)a cooperation project between undergraduate universities in Chongqing and institutions affiliated with the Chinese Academy of Sciences(Grant No.HZ2021018)。
文摘Flexible sensors for high strain sensitivity and dynamic stability are important for the development of human-interactive and health-monitoring devices.However,establishing a stable conductive network with low-conductivity material filling that can resist tensile strain failure and achieve high device performance still faces significant challenges.Herein,a highly stretchable and sensitive strain sensor with strong dynamic stability and low conductive materials filling was fabricated based on highly conductive multi-walled carbon nanotubes(MWCNTs)and Fe nanowires(NWs)to construct a porous-designed bi-conducting network using a salt sacrificial template approach.The porous-designed Fe NW/MWCNT strain sensor(PFMS)with low material filling(3.6 wt.%Fe NWs and 10.6 wt.%MWCNTs)showed high sensitivity with a gauge factor(GF)of 134.98(strain range 0–22%)and 569.37(strain range 22%–60%),which is much higher compared with the pure MWCNT strain sensor with a GF of 7.46.This is attributed to the significant change in the contact area and contact resistance of the Fe NW/MWCNT bi-conducting network during tensile strain.In addition,the PFMS exhibited high repetitive stability over 2000 stretching-releasing cycles.When attached to the human body,the PFMS functions as a health-monitoring device,that can accurately distinguish human motions such as the bending of fingers,knees,and elbows.Finally,the proposed strategy pens a novel avenue for constructing porous conductive networks using polymer composites and is highly competitive for developing high-performance strain sensors.
基金This work was supported by the National Key Research and Development Program of China[No.2020YFB1312900]National Natural Science Foundation of China[No.52105261]Guangdong Basic and Applied Basic Research Foundation[No.2022A1515010316].
文摘Smart structures have the advantages of high system integrity and diverse sensing capabilities.However,the labor-intensive and timeconsuming fabrication process hinders the large-scale adoption of smart structures.Despite recent attempts to develop sensorembedded structures using 3D printing technologies,the reported smart structures generally suffer from the complex fabrication process,constrained part size,and limited sensing modality.Herein,we propose a workflow to design and fabricate novel smart structures via multi-material fused deposition modeling(FDM)-based 3D printing.More specifically,conductive filaments with tailorable mechanical and elec-trical properties,e.g.piezoresistive effects,were developed.Additionally,the printing process was optimized for processing soft filaments with Young’s modulus around 2 MPa,resolving the issue of filament buckling.Furthermore,the potential applications of the proposed workflow were showcased using three design cases,i.e.biaxial strain sensor,smart tire,and cable-driven soft finger with multiple sensing capabilities.This workflow provides a cost-effective and rapid solution for developing novel smart structures with soft materials.
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.