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Solid State Gas Microsensors for Environmental and Industrial Monitoring



R M. Walton, Richard E. Cavicchi, Stephen Semancik, B Panchapakesan, Don L. DeVoe, M I. Aquino-Class, J D. Allen, John S. Suehle


We describe solid state gas microsensor array technology for real-time, low-cost environmental and industrial monitoring. The four-element, surface-micromachined arrays are designed in CMOS technology and consist of multiple platforms called microhotplates. Each microhotplate can be individually addressed, and includes functionality for rapid control and measurement of sensor temperature and gas-induced changes in a sensing film's electrical properties. The array elements can be tuned for specific analytes, by choice of sensing material and the temperature-programs applied, in order to better meet the needs of a particular application. Tin oxide was used as the base sensing material for microhotplates used in these studies. Tin oxide is grown selectively on each individual element within the arrays using a chemical vapor deposition process involving thermal decomposition of tetramethyltin in an argon and oxygen ambient. Catalytic additives such as Pt, Pd, and Cu are surface-dispersed to make the films more selective and sensitive. Detection capabilities for the low power microhotplate sensing technology are being established for target analytes in ambients that are relevant to process control, environmental measurements, and vapor-related remediation studies. We describe use of the micromachined arrays to detect ~ ppm levels of methanol, benzene and hydrogen in ambient air and to produce analyte-specific signatures using temperature programs, T(t).
Proceedings of SPIE


catalyst, environmental monitoring, gas microsensor, micromachined silicon, tin oxide, volatile organics


Walton, R. , Cavicchi, R. , Semancik, S. , Panchapakesan, B. , DeVoe, D. , Aquino-Class, M. , Allen, J. and Suehle, J. (1999), Solid State Gas Microsensors for Environmental and Industrial Monitoring, Proceedings of SPIE (Accessed April 18, 2024)
Created January 1, 1999, Updated February 17, 2017