Integrated implantable device for long-term glucose monitoring

In this study we report the development of an integrated implantable device for glucose monitoring. The dimensions of the device (5.0 x 7.0 x 1.5 cm) allow implantation under the abdominal skin of a large animal for in vivo evaluation of sensor performance. The experimental set-up includes amperometric glucose biosensor, a miniature potentiostat, an FM signal transmitter, a power supply and an antenna and receiver linked to a computer-based data acquisition system. The device performance was evaluated in vitro using a ten-day continuous test and other long-term operation experiments. The biosensor was tested in different model solutions that simulated the physiological environment in which it will be ultimately used. A linear response to glucose concentration was obtained up to 25 mM glucose, with a sensitivity of less than 0.5 microA/mM. The ability of the biosensor to measure glucose levels in serum was also tested, and a good correlation demonstrated between glucose serum levels measured by routine technique and those measured using the biosensor (R2 = 0.993; slope = 0.996). Initial results obtained from the short-term subcutaneous implantation of the sensor demonstrate its potential for the monitoring of glucose concentration in vivo.