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Fast response hydrogel-based plasmonic sensor substrate for the detection of ethanol

: Kroh, Christoph; Wuchrer, Roland; Steinke, Nadja; Günther, Margarita; Gerlach, Gerald; Härtling, Thomas


Cararra, Sandro (Ed.) ; Institute of Electrical and Electronics Engineers -IEEE-:
IEEE Sensors 2019. Conference Proceedings : October, 27-30, 2019, Montreal, QC, Canada
Piscataway, NJ: IEEE, 2019
ISBN: 978-1-7281-1634-1
ISBN: 978-1-7281-1635-8
4 S.
Sensors Conference <18, 2019, Montreal>
Bundesministerium für Bildung und Forschung BMBF (Deutschland)
VIP+; 03VP01970
Fraunhofer IKTS ()
plasmonic sensor; microstructured hydrogel; nanostructured sensor substrate; in-line sensor; ethanol sensor; hydrogel

The inline monitoring of ethanol concentrations in liquids is a crucial part of process monitoring in breweries and distilleries. Current methods are based on infrared spectroscopy which are bulky and costly making them non-affordable for small and middle-sized companies. To overcome these problems, we present a small, compact and cost-effective sensing method, based on a nanostructured, plasmonically active sensor substrate. The sensor substrate is coated with a microstructured ethanol-sensitive acrylamide-bisacrylamide hydrogel which induces a change of the hydrogel’s refractive index in conjugation with the hydrogel swelling and shrinking. With such an approach, the ethanol concentration in liquids can be determined in a simple optical transmittance setup. In our study, we demonstrate the capability of the sensor principle for the detection of ethanol concentration ranging from 0 to 30 vol%. Furthermore, we determined the response time of the sensor substrate to be less than 10 seconds, which shows an enormous improvement compared to other hydrogel-based sensing methods. Finally, initial results for real sample measurements are presented.