A glucose biosensor based on an oxygen electrode: in-vitro performances in model buffer solution and in blood plasma.

An implantable biosensor for continuous monitoring of glucose levels in diabetic patients was developed. The biosensor is based on an amperometric oxygen electrode and glucose oxidase immobilized on carbon powder held in the form of a liquid suspension. The enzyme material can be replaced (the sensor recharged) without sensor disassembly. Sensors with polycarbonate glucose-diffusion membranes coated with silastic were studied. Calibration curves of the sensors in phosphate buffer solution and in undiluted blood plasma at body temperature were obtained and compared. Sensors were tested for long-term performance in vitro in model phosphate buffer solution and in blood plasma at room and at body temperature. Reproducibility of the sensor responses in plasma at body temperature was demonstrated. During continuous operation at body temperature, the sensors have a lifetime of at least six weeks.