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Proceedings Paper

Chemical microsensors based on hydrogels with adjustable measurement range
Author(s): W. Haas; J. W. Bartha; W.-J. Fischer; A. Richter
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Paper Abstract

This work presents polymeric microsensors for the monitoring of alcohol contents in aqueous solutions. The inexpensive sensor device is partially built by polymers. The housing consists of (100) Si substrate, whereas the sensitive material is poly(N-isopropylacrylamide) (PNIPAAm). The acquisition of the sensor data is realized by a non-contact light barrier. The output answer of this light barrier is strong linear. The continuous sensor signal observed by the light barrier is the deflection of an elastic membrane, which is caused by the swelling or deswelling of the stimuli-responsive hydrogel. To achieve an electronic adjustment of the sensor’s measurement range we use a controlled double-sensitivity of hydrogel. By controlling the temperature of the temperature-responsive hydrogel PNIPAAm the phase transition concentration is precisely adjustable to the required value. The electrothermic control interface is based on a Peltier element. The response time of the sensors is in the lower minute range and therefore fast enough for the most of applications. The average sensor resolution for measurements of ethanol is ca. 23mV/wt.-%. The shift of measurable concentration range approximately amounts to 5.6 wt.-% ethanol per 5°C. Further improvements are possible.

Paper Details

Date Published: 17 May 2013
PDF: 7 pages
Proc. SPIE 8763, Smart Sensors, Actuators, and MEMS VI, 87632Z (17 May 2013); doi: 10.1117/12.2018068
Show Author Affiliations
W. Haas, Institute of Semiconductors and Microsystems (Germany)
J. W. Bartha, Institute of Semiconductors and Microsystems (Germany)
W.-J. Fischer, Institute of Semiconductors and Microsystems (Germany)
A. Richter, Technische Univ. Dresden (Germany)

Published in SPIE Proceedings Vol. 8763:
Smart Sensors, Actuators, and MEMS VI
Ulrich Schmid; José Luis Sánchez de Rojas Aldavero; Monika Leester-Schaedel, Editor(s)

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