Preparation Of Stretchable Conductive Materials And Their Applications On Wearable Sensingdevices

Stretchable conductive materials have been widely used in many fields such as health manager materials, pressure sensors and tissue engineering because they are the coalitions of conductivity and flexibility. So far, the most common method to prepare stretchable conductive materials is attaching an ultrathin layer with conductivity to elastomer.In this work, a graphene/polyurethane sponge composite was prepared by impregnating the graphene oxide suspension into shape-cut polyurethane sponge and then the graphene/polyurethane sponge compositewas acquired after chemical reduction. The possibility of the composite to be appropriate for pressure sensor was confirmed by characterization about the relationship of conductivity and ambient pressurewithdigital push & pull tester and RCL digital bridge. then, purposive measurements such as cycling stability, sensitivity and response time were carried out through digital push & pull tester and Auto lab. The results indicated that the cycling stability of the composite turned up to be good enough and the response time was 0.3s,and the sensitivities were 0.17kPa-1 and 0.005 kPa-1 in the pressure range of0~6kPa and 6~25kPa respectively. It can respond in a large pressure range in 0~200kPa and present good sensing performance.However, the sensitivity of the sensors which was applied in monitoring delicate physical signals such as human pulse and heartbeats need to be high enough in the ultralow pressure range(<2kPa).The material with the designed structurewhichwas surface patterned self-supported nanofibrous membrane was fabricated through solution cast of polypyrrole cladded PVA-co-PE nanofiber and POE nanofiber suspension by adopting on a laser scribed silicon template. After observed by SEM, two piece of surface modified nanofiber membrane was assembled face to face to obtain the ultrasensitive pressure sensor. Then the pressure sensors were ordered arranged to verify the potential on electronic skin by testing the performance of the large area pressure sensor after characterization the sensitivity and stability of the single pressure sensor. The sensitivities of that sensor turn out to be 1.24kPa-1、0.89kPa-1and0.02kPa-1in the pressure range of 0-0.15 kPa, 0.15kPa-1kPaand 1-7kPa respectively. At last, a human pulse monitoring system which contains a pressure sensor as a collecting device and a Bluetooth as a delivery device was established. Finally, an export wave which shows the same frequency and similar waveform with electrocardiogramwas recorded and exported by a software installed in an iPhone.