The microfluidic device fabrication and bacterial handling processes have been detailed previously, based on standard and improved fabrication techniques In brief, the microfluidic electrochemical cell was equipped with three electrodes: a graphite working electrode (WE), a graphite counter electrode (CE) (GraphiteStore.com Inc., USA), and a gold pseudo-reference electrode (RE). The WE and CE were cut into strips measuring 3×20 mm and 4×20 mm, respectively. Graphite electrodes were bridge-type electrode, which could avoid contact with sidewalls. Combined with a perpendicular flow, such an approach has been shown by simulation to result in a homogenized boundary layer around the EAB. The pseudo-RE was fabricated by electroless deposition of gold on a polystyrene support and then was cut into 3×20 mm strips. We note that previous work has gone to great lengths to prove that the potential of the pseudo-RE for microfluidic BES was constant at 200 mV vs. SHE under continuous flow. The device included two microfluidic layers. The bottom layer included the main reaction channel with embedded electrodes, two outlets, and a square fluid conduit positioned directly above the working electrode (WE). The upper layer included a short inlet channel that terminated at the square conduit in the lower layer. This design directed the flow perpendicularly against the EAB growing on the WE. A photograph of the final device is shown in Figure , and a schematic is shown in Figure .