| Summary: | 碩士 === 逢甲大學 === 自動控制工程所 === 99 === A novel CO gas microsensor with tungsten oxide (WO3) sensing film on nanoporous anodic aluminum oxide (AAO) layer has been performed on anodic aluminum oxide template at operation temperature of 25 ℃. Based on microelectromechanical system (MEMS) technology, the microstructures are realized with porous AAO template, WO3 thin films, heaters, and interdigital temperature sensors. The platinum films were deposited to form the heaters, temperature sensors, and interdigital electrodes. To enhance sensitivity, the sputtered WO3 was grown on various nanoporous AAO structures. The study develops a novel porous anodic alumina processing system with a functional current feedback control module that provides control different conditions of voltage, temperature, and etching time to obtain uniform size of AAO film in the range from 20 nm to 104 nm. The self-ordered alumina membranes with a wide range of pore sizes are also achieved to increase sensing area of the microsensor. Experimental results are analyzed to find the relationship between the CO gas concentrations, the characterization of sensitivity and operational temperatures. Compared to traditional gas sensors, the designed CO gas microsensors show higher sensitivity by increasing variation of sensing resistance up to 87.4 % by sensing CO gas concentrations from 100 to 1000 ppm.
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