IN-VIVO RECHARGEABLE GLUCOSE BIOSENSORS

The development stages and evaluation of an implantable, rechargeable, glucose sensor for continuous in vivo monitoring of glucose concentra tion are overviewed. The present approach makes it possible to extend the sensor's lifetime by in situ sensor refilling replacing spent immo bilized enzyme with fresh enzyme. In the rechargeable biosensor the en zyme, glucose oxidase, is immobilized on dispersed carbon powder which is then held in a liquid suspension. The construction of the biosenso r is such that the spent immobilized enzyme can be removed from the se nsor body and fresh enzyme suspension is simultaneously injected via s epta, without sensor disassembly or surgical access. The rechargeable sensor body is resistant to all of the standard procedures for sterili zation including autoclaving. The sensor can be refilled with fresh en zyme material after sterilization. Rechargeable sensors based on both hydrogen peroxide and oxygen measuring principles have been under deve lopment. This biosensor, with a miniature potentiostat and signal tran smitter is integrated into a small independently functioning device su itable for canine or other large animal implantation. Evaluation of th e sensors and their recharging protocols in vitro and in vivo are disc ussed.