Dielectric Sensor System Using TiO2 Nanotubes for Real-Time Detection of Methanol Contamination in Alcoholic Beverages

In this article, a portable sensor system based on a TiO2 nanotube array is described for detecting methanol contamination in alcoholic beverages. TiO2 nanotubes were synthesized on a Ti substrate by using electrochemical anodization technique and Au contacts were deposited over TiO2 nanotubes by vacuum-assisted thermal evaporation technique. The TiO2 nanotube array was sandwiched in-between Ti and Au electrodes, which resulted in a capacitive-type structure of the sensor. The conductive and capacitive changes in the sensor operating at room temperature were then tested for pure ethanol, 10% and 25% methanol-contaminated ethanol, and pure methanol. The sensor exhibited a selective capacitive response toward all methanol-contaminated samples and recovered to its baseline capacitance value in less than 40 s. The dielectric sensor was then integrated with a 9-V, battery-driven, signal-processing circuit having a LED for notifying the information on methanol contamination in an alcoholic beverage. The integrated sensor system was able to detect 10%-100% methanol contamination in alcoholic beverages like whiskeys in less than 3 min.