CMOS MEMS Gas Sensors

摘要

Various industrial applications and environmental monitoring require gas sensors so that they develop rapidly. In this paper, the development and principle of gas sensors will be introduced, and the CMOS MEMS humidity sensor and carbon monoxide (CO) sensor developed by my research term will be presented. Both of the gas sensors, which are resistive type, consist of a sensing film, a sensing resistor, a micro heater and readout circuits. The sensing film that is prepared by sol-gel method is coated on the sensing resistor. When the sensing film absorbs or desorbs sensing gas, the sensing resistor changes in resistance. The readout circuits are employed to convert the resistance variation of the sensing resistor into the output voltage. Experiments show that the humidity sensor has a sensitivity of 4.5 mV/% RH at 60 ℃ and the CO sensor has a sensitivity of 1 mV/ppm.