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Proceedings Paper

CMOS-based chemical microsensors: components of a micronose system
Author(s): Andreas Hierlemann; Andreas Koll; Dirk Lange; Christoph Hagleitner; Nicole Kerness; Oliver Brand; Henry Baltes
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Paper Abstract

We report on results achieved with three different types of polymer-coated chemical microsensors fabricated in industrial CMOS technology. The first and most extensively studied transducer is a microcapacitor sensitive to changes in dielectric properties of the polymer layer due to analyte absorption. An on-chip integrated (Sigma) (Delta) -converter allows for detecting the minute capacitance changes. The second transducer is a resonant cantilever sensitive to predominantly mass changes. The cantilever is electrothermally excited, its vibrations are detected using a piezoresistive Wheatstone bridge. In analogy to acoustic wave devices, analyte absorption in the polymer causes resonance frequency shifts as a consequent of changes in the vibrating mass. The last transducer is a microcalorimeter consisting of a polymer-coated sensing thermopile and an uncoated reference thermopile each on micromachined membranes. The measurand is the absorption or desorption heat of organic volatiles in the polymer layer. The difference between the resulting thermovoltages is processed with an on-chip low-noise differential amplifier. Enthalpy changes on the order of (mu) J have been detected.

Paper Details

Date Published: 18 November 1999
PDF: 12 pages
Proc. SPIE 3857, Chemical Microsensors and Applications II, (18 November 1999); doi: 10.1117/12.370283
Show Author Affiliations
Andreas Hierlemann, ETH Zurich (Switzerland)
Andreas Koll, ETH Zurich (Switzerland)
Dirk Lange, ETH Zurich (Switzerland)
Christoph Hagleitner, ETH Zurich (Switzerland)
Nicole Kerness, ETH Zurich (Switzerland)
Oliver Brand, ETH Zurich (Switzerland)
Henry Baltes, ETH Zurich (Switzerland)

Published in SPIE Proceedings Vol. 3857:
Chemical Microsensors and Applications II
Stephanus Buettgenbach, Editor(s)

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