Design Analysis and Fabrication Steps of MEMS Humidity Sensor for Automobile Applications

摘要

Humidity measurement plays a major role in various industries and energy applications. Monitoring and controlling the humidity is of great importance for the reliable operation of various systems. One of the techniques for measuring humidity is the use of absorption capabilities of polymers. Humidity variations change the electrical permittivity of polymers. Therefore, if the polymer is placed between the two plates of a capacitor, the value of the capacitance which can be practically measured becomes a measure for humidity. In micro electromechanical systems (MEMS) the fabrication of two capacitor plates with a polymer material between the plates is feasible. Furthermore, the packaging of such a measuring device including electrical wiring is possible. In this paper, a MEMS polymer capacitor based humidity sensor is designed and its fabrication sequence is laid out. The developed MEMS humidity sensor has fast response and low cost due to its small size. In addition, the humidity sensor power consumption is low and its performance is insensitive to temperature variations which is a great advantage.