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Proceedings Paper

CMOS chemical microsensors based on resonant cantilever beams
Author(s): Dirk Lange; Andreas Koll; Oliver Brand; Henry Baltes
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Paper Abstract

We present a chemical gas sensor based on a resonating cantilever beam in CMOS MEMS technology. The sensor is actuated employing electrothermal actuation. Thus, for a 300 micrometers long beam vibration amplitudes of 6.5 nm per mW heating power are achieved. The vibrations are detected with piezoresistors in a Wheatstone bridge scheme. Detection sensitivities above 200 (mu) V per mW heating power are measured with the bridge biased at 5 V. The beams have quality factors of up to 600. The static power dissipation that goes along with the electrothermal actuation scheme leads to a small temperature elevation of 0.3 K/mW of the sensitive area. The beams are coated with poly(etherurethane) as the sensitive layer. The layer thickness was determined by the change of the initial resonance frequency. Concentrations of octane, ethanol and toluene in synthetic air were measured. For toluene, concentrations as low as 250 ppm can be detected.

Paper Details

Date Published: 20 July 1998
PDF: 11 pages
Proc. SPIE 3328, Smart Structures and Materials 1998: Smart Electronics and MEMS, (20 July 1998); doi: 10.1117/12.320174
Show Author Affiliations
Dirk Lange, ETH Zurich (Switzerland)
Andreas Koll, ETH Zurich (Switzerland)
Oliver Brand, ETH Zurich (Switzerland)
Henry Baltes, ETH Zurich (Switzerland)

Published in SPIE Proceedings Vol. 3328:
Smart Structures and Materials 1998: Smart Electronics and MEMS
Vijay K. Varadan; Paul J. McWhorter; Richard A. Singer; Michael J. Vellekoop, Editor(s)

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