Development of a microcontroller‐based humidity sensing system

This paper documents the development of a microcontroller‐based humidity sensing system. The humidity sensors are manufactured by thin film technology from a novel combination of SiO/In₂O₃. The fabrication and characterization of the sensor samples is presented and discussed in this paper. The sensor pattern consists of an interdigitated conductor on top of which the sensing layer is deposited. A humidity sensitivity of 0.25%/RH% and a thermal sensitivity of 0.103%/°C has been measured. The samples exhibit a low drift over a one‐year time span (0.0013RH%/yr), low hysteresis (0.34RH%), good linearity (±2RH%) and a reasonably fast time response (18 sec). The entire sensor system has been analyzed mathematically and the necessary algorithms for error‐compensation have been developed. The resulting measurement system is efficient, accurate and flexible.