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Open AccessArticle

An Impedance-Based Mold Sensor with on-Chip Optical Reference

Institute for Microsensors, Actuators and Systems (IMSAS), University of Bremen, Otto-Hahn-Allee NW1, Bremen 28359, Germany
Microsystems Center Bremen (MCB), Bremen 28359, Germany
microFAB Service GmbH, Bremen 28359, Germany
Author to whom correspondence should be addressed.
Academic Editor: Alexander Star
Sensors 2016, 16(10), 1603;
Received: 28 July 2016 / Revised: 12 September 2016 / Accepted: 23 September 2016 / Published: 28 September 2016
(This article belongs to the Section Biosensors)
A new miniaturized sensor system with an internal optical reference for the detection of mold growth is presented. The sensor chip comprises a reaction chamber provided with a culture medium that promotes the growth of mold species from mold spores. The mold detection is performed by measuring impedance changes with integrated electrodes fabricated inside the reaction chamber. The impedance change in the culture medium is caused by shifts in the pH (i.e., from 5.5 to 8) as the mold grows. In order to determine the absolute pH value without the need for calibration, a methyl red indicator dye has been added to the culture medium. It changes the color of the medium as the pH passes specific values. This colorimetric principle now acts as a reference measurement. It also allows the sensitivity of the impedance sensor to be established in terms of impedance change per pH unit. Major mold species that are involved in the contamination of food, paper and indoor environments, like Fusarium oxysporum, Fusarium incarnatum, Eurotium amstelodami, Aspergillus penicillioides and Aspergillus restrictus, have been successfully analyzed on-chip. View Full-Text
Keywords: mold; impedance; colorimetric; culture medium; archives; transport containers mold; impedance; colorimetric; culture medium; archives; transport containers
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Papireddy Vinayaka, P.; Van den Driesche, S.; Blank, R.; Tahir, M.W.; Frodl, M.; Lang, W.; Vellekoop, M.J. An Impedance-Based Mold Sensor with on-Chip Optical Reference. Sensors 2016, 16, 1603.

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