ACTIVELY DEPOSITED CERAMIC LAYERS AS INSULATION ON THIN IMPLANTABLE ELECTRODE CONDUCTORS

The electrical and chemical insulation of thin platinum wires insulate d with titanium dioxide or alumina was investigated. These non-conduct ing layers were deposited onto wire surfaces using conducting material s in a unique active sputtering process and were evaluated Sor possibl e use as insulation on implantable electrode conductors. The mechanica l properties of the layers were found to be appropriate for the applic ation, although it was not conclusively established whether these ultr a-thin coatings would provide satisfactory biocompatibility. In vitro evaluation indicated pinholes in the lavers, which permitted contact b etween the underlying metal and the ions iir a saline solution. In viv o evaluation revealed slight inflammatory; responses, probably indicat ive of impurities in the ceramic layers.