Fully implantable miniaturized telemetry based glucose biosensor and real-time video camera implant for tissue biocompatibility studies

Diabetics typically monitor glycemia levels by repeatedly obtaining capillary blood samples by painful finger pricking, sometimes six times a day. Non-compliance can lead to complications like blindness, poor circulation, coma, or death. Continuous glucose monitoring and long-term implanted sensor operation are our ultimate goals.; A subminiature implantable potentiostat and telemetry electronics package was developed for remote monitoring of implantable amperometric glucose sensors. Included are a potentiostat for sensor biasing, transimpedance amplifier to produce the sensor-current proportional voltage, and optically coupled interface to the commercially available telemetry unit which transmits data to a receiver and computer. Potentiostat components were individually tested in vitro, then as a system utilizing telemetry for end-to-end remote data monitoring. In vitro sensor calibrations with our subminiature potentiostat/telemetry unit and traditional potentiostat correlated well (R2 = 0.9994).; An implantable real-time video telemetry system was developed for remote monitoring and evaluation of tissue reactions to an implant such as a biosensor. Experimental biosensor coatings and treatments can be evaluated in situ for improved blood vessel growth, reduced inflammation, and fibrous encapsulation reduction. Continuous non-surgical site testing will save animal lives. The implantable system comprises a fiber optic lens CCD camera, a TV Video transmitter, a 4-LED illumination module, and a 9 VDC battery. The video signal was telemetried to TV sets and video tape recorders having tuners. The 512 by 492 image pixels represent a 1.6 by 1.2 mm field of view. Magnification approaches 200, depending on image size, with 2 mum resolution (4 mum Nyquist). Modulation transfer functions showed resolvability at 90 lp/mm (5.5 mum line), for telemetried and direct images. In vivo and ex vivo images showed blood vessels as small as 5--10 mum in diameter. Various tissue types such as muscle and connective tissue were also distinguishable. Finally, experimental drug delivery microspheres of 10--20 mum diameter were easily distinguishable.; Therefore, we conclude we have developed both an implantable real-time glucose monitoring system, and an innovative video monitoring system to study in vivo tissue reactions and biocompatibility issues.