The overall objective of this program is to use nanostructured porous silicon coatings to enhance the biocompatibility of ceramic-based multi-site neural recording electrode (CBMSE) arrays.Collaborating with K. Moxon of Drexel University, we have already fabricated CBMSE arrays that can chronically record multiple single neuron activity for up to three weeks. However, in order to use these electrodes for long-term studies or as neural interface components of neural prosthetic devices, recordings will have to be maintained for months or even years. We propose to use the porous silicon nanostructures as a scaffold system, attached to the CBMSE array. We anticipate the porous Si scaffold system will a) carry neurotrophic factors to the insertion region of the electrode to minimize neural damage, and b) promote neural growth at the electrode/tissue interface for better contact of the recording sites on the CBMSE array with neurons. To demonstrate the feasibility of this goal in Phase I, Spire, in collaboration with Drexel University, will fabricate single element porous Si-coated CBMSE-based electrodes that will be implanted into a group of laboratory rats and the effect on neural tissue will be evaluated at different time intervals. The neural tissue will be evaluated using histology methods to look for neural damage near the site of implantation and study the growth of neurons into the porous silicon coated electrodes. Dr. M. Frosch, M.D. of Massachusetts General Hospital will assist in interpretation of these histologic findings. In Phase II, upon optimizing the process parameters for producing hybrid porous silicon-CBMSE electrodes, we will design, fabricate and test in-vivo performance of a two dimensional array of this type of electrodes for chronic, long-term (greater than 3 months) multi-site recording. PROPOSED COMMERCIAL APPLICATION: The potential for commercial application of the proposed technology in biomedical industry is immense. Bioactive micro- and mesoporous Si surfaces have the potential to be used in biochip integration, wound repair, drug delivery and reconstructive prosthesis where some material corrosion is actually desirable. For applications which require more surface stability such as in biosensing and biofiltration, macroporous silicon could enable fabrication of a new generation of more advanced and biocompatible devices.