Implantable Electrocatalytic Glucose Sensor

Abstract

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.

Biomolecular sensors for advanced physiological monitoring

“…Many other body fluids, including interstitial fluid (ISF), saliva, tears and urine are derived from blood, making it an excellent reference for alternative fluid comparison. Blood is being explored as a potential fluid for in vivo body-based sensors 139 ; however, its sampling tends to be invasive and risks systemic infections. In addition, blood contains high concentrations of cells and proteins, which can cause biofouling and decrease the stability and reliability of sensors over time.…”

Accuracy of the One-Point in Vivo Calibration of “Wired” Glucose Oxidase Electrodes Implanted in Jugular Veins of Rats in Periods of Rapid Rise and Decline of the Glucose Concentration

“…The incidence of complications of diabetes could be reduced if a reliable, inexpensive, simple to use, innocuous, and continuous blood glucose monitor were available. This is well recognized, and much work is done worldwide on electrochemical, − transdermal, − and spectroscopic monitoring − of glucose in vivo. The electrochemical sensors reported differ in their implantation method and site; size; solution-contacting, reactant-permeating area; response time; need for and method of calibration; operational life; and minimal elapsed time following implantation at which the sensor can be calibrated and used.…”