Behavior of a Microelectrode with a Concentrated Enzyme-Immobilized Layer

The behavior of electrodes with a highly concentrated enzyme-immobilized layer was examined. The enzyme-immobilized layer was formed by placing a droplet of an enzyme solution on the working electrode surrounded by a super-hydrophobic layer and shrinking it by evaporation. A significant increase in the output current was observed compared electrodes fabricated by a conventional method. The current density increased by decreasing the electrode size and increasing enzyme loading. The sensor fabricated by this method was incorporated in a micro-flow channel. With smaller electrodes, the current density and the conversion efficiency increased and the flow dependence became weaker. The sensitivity and the conversion efficiency could also be improved by placing two same electrodes in the flow channel.