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Cobalt Oxide Nanosheet and CNT Micro Carbon Monoxide Sensor Integrated with Readout Circuit on Chip
Department of Mechanical Engineering, National Chung Hsing University, Taichung, 402 Taiwan
Department of Mechanical and Electro-Mechanical Engineering, Tamkang University, Tamsui, 251 Taiwan
Microsystems Technology Center, Industrial Technology Research Institute, Tainan, 709 Taiwan
* Author to whom correspondence should be addressed.
Received: 31 December 2009; in revised form: 30 January 2010 / Accepted: 4 February 2010 / Published: 3 March 2010
Abstract: The study presents a micro carbon monoxide (CO) sensor integrated with a readout circuit-on-a-chip manufactured by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and a post-process. The sensing film of the sensor is a composite cobalt oxide nanosheet and carbon nanotube (CoOOH/CNT) film that is prepared by a precipitation-oxidation method. The structure of the CO sensor is composed of a polysilicon resistor and a sensing film. The sensor, which is of a resistive type, changes its resistance when the sensing film adsorbs or desorbs CO gas. The readout circuit is used to convert the sensor resistance into the voltage output. The post-processing of the sensor includes etching the sacrificial layers and coating the sensing film. The advantages of the sensor include room temperature operation, short response/recovery times and easy post-processing. Experimental results show that the sensitivity of the CO sensor is about 0.19 mV/ppm, and the response and recovery times are 23 s and 34 s for 200 ppm CO, respectively.
Keywords: micro carbon monoxide sensor; cobalt oxide film; readout circuit
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Dai, C.-L.; Chen, Y.-C.; Wu, C.-C.; Kuo, C.-F. Cobalt Oxide Nanosheet and CNT Micro Carbon Monoxide Sensor Integrated with Readout Circuit on Chip. Sensors 2010, 10, 1753-1764.
Dai C-L, Chen Y-C, Wu C-C, Kuo C-F. Cobalt Oxide Nanosheet and CNT Micro Carbon Monoxide Sensor Integrated with Readout Circuit on Chip. Sensors. 2010; 10(3):1753-1764.
Dai, Ching-Liang; Chen, Yen-Chi; Wu, Chyan-Chyi; Kuo, Chin-Fu. 2010. "Cobalt Oxide Nanosheet and CNT Micro Carbon Monoxide Sensor Integrated with Readout Circuit on Chip." Sensors 10, no. 3: 1753-1764.