Electrocatalytic glucose sensor.

An electrocatalytic glucose sensor for in vivo application has been developed. The sensor is a flow-through cell with three electrodes and can be integrated into a blood vessel. The principle of measurement is based on the direct electrochemical oxidation of glucose at a membrane-covered noble-metal electrode. To test the potential long-term in vivo function of the sensor, it was implanted in the carotid artery of a sheep. Thus, the sensor performance was verified over a period of 71 days. During this time, a nearly constant blood flow through the cell was achieved, which indicates good blood compatibility of the materials used. It was possible to set up a calibration that was valid over 24 days (mean error 2.3 mmol l-1). The tested cross-sensitivity of the sensor towards cysteine, acetyl salicylic acid and other small molecules shows tolerable effects on this type of glucose measurement. Only high concentrations of lactate and ethanol require a special adaptation of the calibration to suppress their influence. Minor cross-sensitivity and promising long-term stability recommend this type of sensor for in vivo monitoring of blood sugar level. However, for intravasal application, it is necessary to modify the present sensor design to a catheter-type construction.