MEDIATED MICRO-GLUCOSE SENSORS USING 2 MU-M PLATINUM-ELECTRODES

Glucose-oxidase (GOD) and glucose-dehydrogenase (GDH) immobilized cylindrical microelectrodes were fabricated, and their characteristics were evaluated by using 1,4-benzoquinone and ferricyanide as electron mediators, respectively. Each enzyme was immobilized in a photocrosslinkable polymer on a cylindrical microelectrode of 2 mum diameter. A linear range in the calibration plot of the GOD-based micro-glucose sensor was observed to be wider than that obtained using a disk electrode of 1 mm diameter. The mediated response of the 2 mum glucose sensor was compared with the response resulting from hydrogen peroxide detection. This result showed that a higher response and a wider linear range were observed at a highly concentrated mediator. For the GDH-immobilized 2 mum microelectrode, a much higher response was obtained when not only ferricyanide but also diaphorase were employed to reoxidize NADH produced by the enzyme reaction of GDH. The GDH-based micro-glucose sensor was found to be unaffected by dissolved oxygen concentration.