Design,Preparation And Properties Research Of Flexible Strain Sensor Based On Carbon Material

Flexible electronic devices offer unlimited potential for the development of wearable devices.Among them,flexible strain sensor has been widely concerned because of its high flexibility and excellent sensing performance.Traditional metal and semiconductor based strain sensors have excellent detection performance,but they are rigid,which greatly limits their application in wearable devices.The flexible strain sensor based on carbon nanomaterials/polymers has good biocompatibility and can perfectly fit the complex surface of human body,which has high application value in health care,electronic skin and other fields.At present,there are still many technical bottlenecks in this kind of devices.For example,how to solve the contradiction between the sensitivity(GF)of the flexible strain sensor and the measurement range,how to simplify the manufacturing process and reduce the cost of the device,and how to achieve large area preparation.In this study,using polydimethylsiloxane(PDMS)as a flexible substrate,carboxylated multi-walled carbon nanotubes(MWCNT-COOH)and graphene nanosheets(GNFs)with excellent mechanical and electrical properties as conductive materials,two kinds of flexible strain sensors for intelligent health monitoring were designed and fabricated by self-assembly method.We study the performance and application of the sensor as follows:(1)GNFs nanofilms were prepared using Marangoni effect and transferred to PDMS substrate.After encapsulation,PDMS/GNFs/PDMS flexible strain sensors were prepared.The sensor has good response to tensile strain,the strain sensing range is0-20%,the fastest response time is 80 ms,the sensitivity is up to 1087.97,and has the characteristics of light weight,ultra-thin,high stability(300 cycle test).The device can detect the strain signal at different positions such as human pulse,facial muscle movement and joint movement.(2)Multilayer MWCNT-COOH thin films were self-assembled on PDMS flexible substrate by layer self-assembly(LBL)method,and GNFs nanofilms were assembled on the surface of the thin films.After encapsulation,PDMS/MWCNT-COOH/GNFs/PDMS flexible strain sensors were prepared.The sensor performance of the device is improved by the cooperative conductive network of MWCNT-COOH and GNFs.And the serpentine pattern design of the conductive layer structure of the device ensures that the device can take into account both high sensitivity and low power consumption performance.The device has a strain sensing range of0-50%,a short response time(112 ms),a sensitivity of up to 2169,and excellent durability(1000 cycle tests).In addition,in the practical application test,the device can accurately detect the P,T and D peaks of human pulse,and regularly respond to other movements of human body such as breathing,facial muscle movement and large strain movements such as finger bending and bending the knee.In summary,the flexible strain sensor prepared in this paper can realize the perception of tensile function,has excellent sensitivity,linearity and stability,and can realize the effective monitoring of human movement,showing a good application prospect in wearable devices,artificial intelligence and other fields.