The miniaturization of neuroprosthetic technology has led to an urgent need for thin (10 mu m or less) insulating coatings that retain their biocompatibility and stability over long periods. Initiated Chemical Vapor Deposition (iCVD) is an alternative to applying polymers using solvent-based techniques or a powder spraying methods. Under the Phase I funding, an iterative process was used to identify a window of iCVD processing conditions that successfully provided electrical insulation to 25 mu m diameter gold lead wires. The coating was tested after physical stressing and exposure to a simulated biological environment and the integrity, adhesion, and insulating abilities of GVD's PTFE coating were proven in short-term testing. A key study in the Phase I project was the comparison between GVD's PTFE coated wires and other leading commercial coatings including Parylene-C, silicone, and commercially available Teflon(r) coatings. Our study showed that GVD's PTFE coating out-performed all other coatings by providing enhanced electrical insulation while reducing the overall wire diameter. The goal of the Phase II project is to expand the use of thin iCVD PTFE coatings for insulating and protecting neural probe assemblies. This will be accomplished by designing equipment capable of coating sufficient numbers of prototypes for testing, optimizing the process for coating 3D substrates, further research into adhesion promotion strategies for the substrates of interest and long term testing of the coating's biocompatibility. The new equipment will allow us to coat wires of different materials and several types of neural prosthetic prototypes for evaluation and long-term testing. The ultimate goal is to achieve single step encapsulation of three-dimensional neural probe arrays and of neural prosthetic assemblies. At the end of this Phase II work, GVD will be able to offer to researchers and manufacturers a proven, effective solution to the problems of insulation and encapsulation of neuroprosthetic devices. This will enable greater flexibility in the design of these devices, the choice of materials used, and the minimum dimensions which can be achieved. The therapeutic benefit will be to de-bottleneck the development of these devices and accelerate their proliferation as treatments for neurological disorders.
