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

Abstract

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.

Adaptive-Cognitive Kalman Filter and Neural Network for an Upgraded Nondispersive Thermopile Device to Detect and Analyze Fusarium Spores

“…According to Fusarium management guide [8], Fusarium head blight disease, which is the key factor to cause Fusarium damage kernel on wheat, has annually resulted in losses of hundreds of million dollars. Many other previous studies of analyzing and detection Fusarium were conducted by applying mass spectroscopy [9], Fourier transform infrared spectroscopy, near-infrared spectroscopy [10,11], polymerase-chain-reaction machine [12], chlorophyll fluorescent imaging [5] or impedance-based gold-electrodes sensor [13]. Though these mentioned approaches are effective, some drawbacks can be seen such as expensive, complex to manipulate and hard to achieve quick detection.…”