Development of novel micro-sensor of disposable chips with oxygen enrichment by pre-electrolysis for monitoring blood glucose

摘要

Monitoring blood glucose level is an important procedure for any diabetic subject. The blood, however, has oxygen tension less than 5%. Since the oxygen in the sensor membrane is consumed by the enzyme reaction, the oxygen concentration is neededhigh enough for a better linearity between output current and the glucose concentration.In this monitor, the oxygen is generated by electrolysis of the solution before monitoring, and the glucose concentration is monitored by a peak current obtained by a potential sweep method. A theoretical analysis was made considering diffusions ofglucose, oxygen and hydrogen peroxide, and also the rate of the two-substrate reaction catalyzed by glucose oxidase (GOD) within the enzyme membrane. Concentrations within membranes were analysed by a model of three layers of the solution, the overcoatgel and the enzyme membrane.The output current increased with time after sweeping the potential anodically and had its maximum in 10-20 s. The peak current was linearly proportional to the glucose concentration up to 500 mg dl{sup}-1 by the supplement of oxygen generated byelectrolysis of the solution. The peak current was well simulated by a mathematical model. When one minute is adopted to this monitor, the optimum conditions of M{sub}G, enzyme membrane thickness and electrolysis time were determined to be 1.9-3.8,4.7-9.4μm and 5-10 s, respectively.