Microfabricated, continuous-flow, microbial three-electrode cell for potential toxicity detection

Bioelectrochemical microfluidic devices are developed based on the continuous flow mode of membrane-less, microbial three-electrode cells (M3Cs). These novel devices are the miniaturized microfluidic-based three-electrode cells for the first time, and these are composed of an Ag/AgCl reference electrode, indium tin oxide anode and cathode electrodes. The basic performance of the devices is tested using biofilms grown from wastewater inoculum in an experiment that senses for toxic materials. The toxic materials used are: sodium cyanide, imidazole, and sodium azide in concentrations of 0.02–0.8 mM, with lactate and sodium acetate functioning as substrates. While a constant potential of 0.2 V is applied to the working electrodes of the device, the bioelectrocatalytic oxidation current is monitored at 35°C. When the biocides are introduced, the response current from the cell decreases. The sensor can detect imidazole at the range of 0.02–0.4 mM. The experimental results show the potential of using microfluidic-based microbial electrolysis cells not only as biocide sensors, but also as investigative tools for microbial electrochemical assays.