Talc-impregnated polyimide for humidity sensors with improved hysteresis

This paper reports on the design and synthesis of a talc-impregnated polyimide film exhibiting reduced relative humidity (RH) hysteresis. The morphology of both simple polyimide and talc-impregnated polyimide RH sensing layers are investigated by means of Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). When deposited on quartz crystal microbalance (QCM) substrates, the talc-impregnated polyimide layer yields a highly linear response and a resonant frequency hysteresis improvement as high as 36% with respect to simple polyimide. These experimental results recommend the proposed layer as suitable for high performance RH capacitive sensors.