Preparation Of Carbon Nanotube/Ecoflex Silicone Film Materials And Wearable Application Research

With the emphasis on health care and health monitoring,wearable electronic devices that can realize portable and customized treatment have been developed rapidly.As a class of flexible electronics widely used in wearable devices,conductive elastomer materials have excellent mechanical deformability and reversibility,and can keep excellent mechanical and electrical properties in long-term mechanical environments of bending,compression or tension.However,the preparation of conductive elastomer materials with excellent performance is often complicated or expensive,which limits the preparation and application of conductive elastomer materials for wearable electronic devices.In this paper,CNTs/Ecoflex silicone thin film materials with excellent mechanical properties were prepared by air spray method based on carbon nanotubes(CNTs)conductive fillers and Ecoflex silicone flexible substrates,which solved the problem that CNTs and silicone based thin film materials are difficult to be prepared in a controlled and batch manner.The performance of the CNTs/Ecoflex films was characterized and evaluated for use in wearable devices such as resistive strain sensors,electric heaters,and capacitive pressure sensors.The results of the paper provide theoretical and experimental basis for the development and mass production of conductive elastomers and their wearable applications.The main contents of the paper are as follows:(1)CNTs/Ecoflex silicone films with a granular surface structure were prepared by air spray method and characterized for different component concentrations.The 5 wt% material has excellent electrical conductivity(37.93 S/m)and superior mechanical stretchability(178 %strain),and has the potential to be used as a wearable electric heater.(2)CNTs/Ecoflex thin film material with CNTs concentration of 1 wt% was prepared to construct wearable resistive strain sensors with high sensitivity(GF=1897),wide sensing range(>300 % strain),and high durability(>10,000 cycles of stretching),and its ability to be used for monitoring human joint activities was verified in the paper.In addition,the paper prepared CNTs/Ecoflex/spandex fabric conductive fabric to construct resistive sensors with GF=5 within50 % strain and to monitor joint flexion activities such as fingers,elbows and knees.(3)The paper prepared thin film material with CNTs concentration of 5 wt%,which possesses excellent electrical heating performance as a wearable electric heater,capable of heating up to 62 ℃ at an applied voltage of 10 V and still maintaining stable heating under dynamic heating environment.In addition,a capacitive pressure sensor was prepared by constructing a rectangular conductive pattern on the surface of the foamed powder/Ecoflex porous dielectric layer by air spray method,which can monitor the compressive stress signal within 30 kPa.The paper also prepared 10×10 resolution array type capacitive sensors by spray method,which can monitor the pressure signals at different array locations.