Totally implantable real-time in vivo video telemetry monitoring system for implant biocompatibility studies

An implantable real-time video telemetry monitoring system was developed for remote monitoring and evaluation of tissue reactions to an implant such as a biosensor. Experimental coatings and treatments to improve the function of an implant can now be evaluated in situ and in real-time for improved blood vessel growth (angiogenesis), reduced inflammation, and reduction of foreign body encapsulation. A tissue site can be viewed, recorded, and evaluated for a continuous time period without surgical intervention, thereby saving animal lives. The implantable system comprises a miniaturized fiber optic lens-based CCD camera, a TV video transmitter, a 4-LED illumination module, and a 9 VDC battery source. The TV video signal is telemetried out to a TV set or video tape recorder having a tuner. The 512×492 display or printout image pixels represent a 1.6×1.2 mm field of view by virtue of a 1:3 tapered (3X optical magnification) lens. The apparent magnification thus can approach 200 power with a 200 μm resolution (4 μm Nyquist). Test pattern modulation transfer functions showed resolvability at 90.5 1p/mm (5.5 μm line width) for both telemetried and direct captured images. In vivo and ex vivo rat tissue images showed blood vessels with diameters of 5-10 μm. Various tissue types, such as muscle and connective tissues, were distinguishable, as were experimental drug delivery microspheres of 10-20 μm in diameter. Therefore, we conclude that we have developed a new tool to study tissue reactions to implants