Study of the Gas Sensor Array Based on Micro-Machined Ceramic Hotplate

Abstract

In order to improve the thermal stability of silicon micro hotplate, a ceramic hotplate with structure of suspending bridge was designed. The steady-state thermal response of the hotplate and the structure of the micro-heater were simulated by using the finite element method. By using conventional microelectronics technology and laser micro processing technology, the microstructures with thickness of 100 μm and bridge width of 2 mm were produced. The test results show that the ceramic hotplate has higher working temperature than traditional silicon hotplate, and it can be worked steadily at the average temperature of 630 °C on 1.5W heating power. Taking ceramic hotplate as heating platform and nano-SnO2 materials with Pd doping concentration of 0.2 at.% and 10 at.% as sensitive materials respectively, the array with two gas sensors was designed and fabricated. The gas sensor array can be used to detect single gas of CO or CH4 with high sensitivity and good selectivity when it works with constant heating voltage. When the sensor array works with periodic voltage heating pulse, it can realize quantitative detection for mixed gases of CO and CH4.