Nanostructured porous silicon scaffolds for improved biocompatibility of thin film microelectrodes

The promise of multichannel thin film microelectrodes for closed-loop neural prosthetic control has been hindered by the inability of these electrodes to record for long periods of time. Recently, we have shown that thin film electrodes produced using a ceramic substrate and insulation (CBMSE arrays) can record single neuron action potentials for three months in the rat, which is comparable to microwire electrodes. To enhance their biocompatibility and increase the recording time, we suggest that a porous, biocompatible surface modification of the electrode can be used to anchor the electrode to the neural tissue and thereby, reduce tissue damage creating during long-term implantation of the electrode. We have optimized the process parameters for producing biocompatible porous silicon nanostructures. We have modified the surface of our microelectrodes with nanostructured porous silicon. The porous silicon (PS) layers are up to 50 μm thick with porosities in the range of 10 to 75%. This porous silicon layer has been successfully attached to our thin film ceramic electrodes.