Microelectronic moisture sensor from variable dielectric capacitances of polyimide film

摘要

Three moisture sensors were investigated which use the moisture-dependent dielectric constant of a polyimide film as the sensing variable. The sensitivity varies from 0.04 to 0.7 pF/%RH, the response time varies from 4 to 1000 s, and the temperature sensitivity varies from negligible to 0.05 pF/ degrees C. A hybrid microcircuit was designed and fabricated which converts the sensor's capacitance to a voltage.