IMPLANTATION OF A REFILLABLE GLUCOSE MONITORING-TELEMETRY DEVICE

This study describes the components and short-term in vivo evaluation of an integrated implantable system consisting of an amperometric gluc ose biosensor, a miniature potentiostat, a FM signal transmitter, and a power supply. The device (dimensions: 5.0 x 7.0 x 1.5 cm) was implan ted subcutaneously in healthy mongrel dogs. The biosensor performance was evaluated in vitro prior to implantation using standard solutions simulating the physiological environment. A linear response to glucose concentration was observed throughout the physiological and pathophys iological range (with an upper limit of 25 mM glucose, and a sensitivi ty of 0.5 mu A/mM). The results of short-term subcutaneous implantatio n of the integrated system demonstrated good agreement between the glu cose concentration measured by the biosensor and that obtained using s tandard glucose determination methods. The delay-time between the tiss ue glucose level (measured by the biosensor) and the blood glucose lev el (obtained by standard methodology) was 3-7 min. These results demon strated the feasibility of data transmission by a telemetry system thr ough the skin of a dog and allowed the commencement of chronic in vivo testing. During the chronic implantation the biosensor was refilled i n vivo. A rejuvenation of the sensor's response after refilling was ob served suggesting the potential of such sensors for long-term implanta tion. (C) 1997 Elsevier Science Limited.