An electrocatalytic glucose sensor for in vivo application has been developed to determine
the glucose level in blood and further to control the insulin dosage in a closed loop
system for diabetes therapy. The principle of the electrocatalytic glucose sensor
is based on the direct electrochemical oxidation of glucose at a membrane-covered
platinum electrode. For a possible clinical application the sensor was built as a
catheter. A set of implantations in the vena cava of sheep demonstrated the potential
feasibility of the sensor. The sensor values were simultaneously checked by the enzymatic
analysis of glucose in blood samples drawn separately from a femoral vein. It was
possible to determine the glucose concentration in sheep for more than 130 days with
tolerable deviations from glucose reference measurements. The mean error was 2.5 mmol/l.
One of the catheters was explanted after 211 days and the histological examination
revealed a good biocompatibility of all materials used. In additional experiments,
the differences of the glucose concentration in vena cava as well as in the anterior
and posterior femoral veins of a sheep were examined during glucose tolerance tests.
These experiments verified our method of in vivo calibration of the long-term implantable
glucose sensor.
Glucose Sensor - Electrocatalytic Glucose Measurement - Impedance Method - In Vivo
Measurement - Long-Term Stability - In Vivo Calibration
