Performance And Study On Preparation Of Flexible And Low Hysteresis Sensor Based On Conductive Polymer Composites

Conductive polymer composites(CPCs)have been developed to serve as promising candidates for strain sensors on the basis of excellent flexibility,cost-efficiency and good processibility.In recent years,stretchable strain sensors have attracted considerable attention in extensive application of flexible electronic skin,human motion detection,human-machine interface,soft robotics and artificial intelligence.As for these applications,significant works have been devoted to meeting requirements of high linearity,low hysteresis,good sensitivity,fast responsive time,low detection limit and long-term sensing stability.However,it remains a great challenge for the strain sensors to realize these sensing performances synchronously.In this work,the polydimethylsiloxane(PDMS)foam and double helix elastomer are used as flexible polymer substrates,respectively;carbon black(CB)nanoparticles and intrinsic conducting polymer polyaniline(PANI)are employed as conductive fillers.Through sacrifice template method,ultrasonic dispersion and in-situ synthesis method,the conductive fillers are stably decorated onto the flexible polymer substrates,constructing an excellent conductive network.Then the morphology and sensing performance for the resulted CPCs are investigated systematically,and the concrete content is as follows:(1)Fabrication and investigation of PDMS/CB conductive composite foam with high linearity and low hysteresis and good sensitive propertiesPDMS foam with excellent elasticity as flexible matrix and CB nanoparticles as conductive filler are employed to prepare PDMS/CB foam materials through template method and ultrasonic dispersion technology.Meanwhile,the micro-morphologies show that CB nanoparticles are uniformly distributed on the surface of PDMS foam,thus developing a relatively complete three-dimensional conductive network;at the same time,through infrared analysis,it can be seen that there is a certain interface interaction between CB and PDMS matrix,which makes the constructed three-dimensional conductive network more stable.PDMS/CB conductive foam material possesses excellent linear response(0-70%strain range,R~2(28)0.996)and very low electrical hysteresis(degree of hysteresis under 60%strain is 1.2%).In addition,the PDMS/CB conductive foam material has a large strain range(76%),high sensitivity(8.3),fast response time(100 ms),and long-term durability((29)20100stretching/releasing cycles).The PDMS/CB conductive foam material can be used to detect human motion signals,including monitoring large-strain human motion signals(walking,stepping,running,elbow bending,etc.),and small strain signals,such as bulging,weak muscle movements and swallowing.PDMS/CB conductive foam material also shows good sensing stability and repeatability,and it shows good application prospects in the field of flexible wearable devices.(2)Preparation and investigation of Fiber/PANI/CB conductive composite fiber with low hysteresisThe double helix elastic fiber as the matrix material and PANI and CB as the conductive fillers are used to fabricate Fiber/PANI/CB conductive composite material through in-situ polymerization and ultrasonic dispersion technology.Morphology observation has shown that PANI nanoparticles are uniformly distributed on the surface of elastic fibers,and CB nanoparticles are uniformly loaded on the surface of Fiber/PANI composite,thus developing a stable conductive network.Due to the excellent elasticity of the fiber matrix,low electrical hysteresis(5.1%at 40%strain),large strain response range(200%),and high sensitivity(the sensitivity is 10 when the strain is 0-10%),fast response time(60 ms/80 ms)and high durability((29)10000 cycles tensile test).Low detection limit(0.5%strain)and excellent bending response durability((29)3000 cycles bending/releasing cycles).The conductive composite fiber can be used for monitoring diverse human movements and performing human-computer interaction,which provides a new idea in designing and constructing a flexible wearable strain sensor with a large strain range and high sensitivity simultaneously.