Development of an Innovative Micro Capacitive Humidity Sensor With Double Polyimide Films and Interlacing Out-of-plane Electrodes Structure

This paper presents the design, fabrication and complete characterization of an innovative capacitive relative humidity (%RH) microsensor. The double polyimide (PI) thin films adopted in this study function as a humidity sensing layer and a protecting layer of top electrodes respectively. To improve the humidity sensitivity and responding speed, interlacing out-of-plane electrodes are designed in the RH microsensor. The very low hysteresis (0.24 %RH), high sensitivity (1.25 pF/%RH), high accuracy (plusmn1.12 %RH) and fast response (within 1 second) characteristics of the RH microsensor have been demonstrated in this research.