Mediated micro‐glucose sensors using 2 μm 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 μm 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 μm 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 μm 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.