(2i) Vapor Deposited Polymer Coatings for Implantable Neuroprosthetic Devices

Neuroprosthetic implants are silicon based microelectronic devices that are designed to send and receive electrical signals to and from neurons in the central nervous system. An important part of the fabrication and performance of these devices is the protection of the integrated circuitry from the corrosive effects of the in-vivo environment. In addition, the implantation of these devices is often accompanied by the formation of scar tissue around the implant, which effectively insulates the stimulating and recording electrodes of the implant, thereby interfering with performance.

With these facts as motivation, the goal of the current research is to create polymer thin films that are biocompatible, well-insulating, have good adhesion to silicon, and actively mitigate scar tissue formation. A cyclic siloxane-acrylic acid copolymer is chosen for this purpose; the siloxane providing the desired biocompatibility, insulating characteristics and silicon adhesion, and the acrylic acid providing COOH tether points for the attachment of proteins known to mitigate scar tissue formation and enhance neural proliferation. Chemical Vapor Deposition, a vapor phase polymerization technique, is chosen to avoid the surface tension limitations associated with liquid phase polymerization techniques.