A capacitive humidity sensor based on flexible PTFE substrate

Because of the extensive application prospect of flexible electronics, a capacitive humidity sensor fabricated on a flexible porous Polytetrafluoroethylene (PTFE) substrate is reported in this paper. Silver nanowires as a floating electrode were dispersed onto a PTFE substrate. Then, as humidity sensitive material, polyimide (PI) was spin-coated onto the silver nanowires. Finally, a pair of interdigitated aluminum electrodes were sputtered onto the PI directly through a stencil mask. According to the test results at 20°C and the frequency of 100kHz, the porous PTFE substrate can reduce the response time by 71% and the recovery time by 75% as well as the hysteresis, which shows PTFE is a promising material as a humidity substrate.