An optical MEMS sensor utilizing a chitosan film for catechol detection

Catechol is a widely studied phenol that is a common byproduct of factory waste. The presence of catechol in drinking water and food poses a safety concern due to its toxic and possibly carcinogenic effects. We report the successful fabrication and testing of an optical MEMS sensor for the detection of catechol. Studies on catechol detection have shown that byproducts from catechol oxidation will react with a chitosan film and induce a significant absorbance change in the UV and near UV range. Our reported sensor takes advantage of this unique absorbance property to detect catechol by measuring the change in light intensity at 472 nm through an electrodeposited film of chitosan on a transparent, conductive film of indium tin oxide. This optical detection technique eliminates the nonspecific response from the common antioxidant, ascorbic acid, which does not cause an absorbance change. Absorbance measurements were performed over 10 min while applying an oxidizing current density of 4 A/m2. We observed a considerable response even for our lowest measured concentration (1 mM) while the detection limit of the device is found to be about 0.2 mM for a 10 min reaction time.