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In this paper we discuss the design, fabrication, and modeling of an electrostatically actuated transducer that is operated in a resonant mode. The transducer is designed for gas sensor applications. The microstructure with high-aspect ratio laminated beam or bridge suspensions, has been fabricated using a 0.6 μm three metal, double poly CMOS process. The fabricated chip was post processed by a sequence of two maskless dry etching steps. A thin sorbent polymer layer is included in the design of the microbeam chemical sensor. The devices were designed to provide a relatively large surface area to coat with the sorbent polymer. Gas sorption in the polymer layer can be monitored as a function of the resonant frequency of the device. The device frequency is measured by piezoresistors mounted in a Wheatstone bridge configuration. The fabricated sensors are intended for use in monitoring hazardous gases and vapors. In order to optimize the device resonant frequencies, a variety of microbeam structures were designed with different dimensions. These structures were modeled with a finite element analysis program. A number of selected structures were fabricated in a single chip design.
Circuits and Systems, 2003. ISCAS '03. Proceedings of the 2003 International Symposium on (Volume:3 )
Date of Conference: 25-28 May 2003