Abstract
A methanol microsensor integrated with a micro heater manufactured using the complementary metal oxide semiconductor (CMOS)-microelectromechanical system (MEMS) technique was presented. The sensor has a capability of detecting low concentration methanol gas. Structure of the sensor is composed of interdigitated electrodes, a sensitive film and a heater. The heater located under the interdigitated electrodes is utilized to provide a working temperature to the sensitive film. The sensitive film prepared by the sol-gel method is tin dioxide doped cadmium sulfide, which is deposited on the interdigitated electrodes. To obtain the suspended structure and deposit the sensitive film, the sensor needs a post-CMOS process to etch the sacrificial silicon dioxide layer and silicon substrate. The methanol senor is a resistive type. A readout circuit converts the resistance variation of the sensor into the output voltage. The experimental results show that the methanol sensor has a sensitivity of 0.18 V/ppm.
Highlights
Methanol sensors can be applied in electronic noses [1,2], fuel cells [3], disease diagnosis [4] and environment Monitoring [5]
The tin dioxide doped cadmium sulfide is adopted as the sensitive film of the sensor, and the film is deposited on the interdigitated electrodes
The power supply supplied a voltage to the heater, and the infrared thermometer detected the temperature of the heater
Summary
Methanol sensors can be applied in electronic noses [1,2], fuel cells [3], disease diagnosis [4] and environment Monitoring [5]. Many methanol microsensors have been fabricated using micromachining technology. Tang et al [13] proposed a micro methanol sensor fabricated using MEMS technology. The sensitive material of the sensor was epoxy acrylate polymer. The structure of the gas sensor contained a MEMS microhotplate platform with interdigitated electrodes, and the sensitive material was deposited on the microhotplate platform using the micropipetting. Rahman et al [17] developed a methanol sensor using micromachining technology. The sensitive material of the sensor was silver oxide doped zinc oxide nanoparticles prepared by the hydrothermal method using reducing agents in alkaline medium. The sensitivity of gas sensor was 0.03 Hz/ppm for methanol vapor. The methanol sensor needs a post-COMS process to release the suspended structures and to coat the sensitive material. A readout circuit is utilized to convert the resistance of the sensor into the output voltage
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