Current approaches to interfacing with the nervous system mainly rely on stiff electrode materials, which work remarkably well, but suffer degradation from chronic immune response due to mechanical impedance mismatch and blood-brain barrier disruption. This current technology also poses limits on recording depth, spacing, and location. In this project we aim to ameliorate these issues by developing a system of very fine and flexible electrodes for recording from nervous tissue, a robotic system for manipulating and implanting these electrodes, and a means for integrating electrodes with neural processing chips. We have fabricated six versions of the electrodes, and have demonstrated their manual and automated insertion into an agarose tissue proxy, ex-vivo brain, and in-vivo rat using a micro-welded. We have also fabricated and tested in rats four revisions of the inserter robot. The most recent inserter robot design uses replaceable cartridges for the electrodes, to which electrodes are mounted; these electrodes are made on a 4um thick polyimide substrate with a parylene peel-away backing. The parylene backing holds the fine wires and keeps them from tangling until they are inserted, and provides a more robust means of handling and mounting the structures. Similarly, both the insertion needle and micro-drill can be replaced intra-operatively via cartridges. We have developed a machine for micro-brazing the insertion needle. In vivo tests of the system are ongoing, but we have shown that the electrodes record neural activity well, and are currently assessing longevity and histological response.
Project end date: 01/30/17