Energy transmission across intact skin for powering artificial internal organs.

The prototype for a transcutaneous energy transmission system (TETS) meets the engineering goals of high efficiency, limited heating of surrounding tissues due to losses in implanted components, and excellent resistance to misalignment and uncoupling of the coils. Higher efficiencies, reduced thermal generation, and lighter implanted components are the goals of future designs. Improvements will be made based on the findings of a complete in vitro electrical characterization of the present system, varying operating frequency, the number of turns in the 2 coils, and the voltages and currents in the 2 coils. The results of short-term in vivo studies indicate that the temperature rise in tissues surrounding the implanted components is not excessive, that the layer of cutaneous tissue covering the secondary coil is viable and that the thickness of the tissue separating the 2 coils stabilizes after about 2 wks. Definitive statements await the results of in vivo studies lasting longer than 6 mos. Similarly, an evaluation of the effectiveness of butyl as a moisture barrier awaits the results of long-term in vivo, and in vitro immersion test.