New class of chronic recording multichannel neural probes with post-implant self-deployed satellite recording sites

This paper introduces a new design for microprobes used in recording signals from neural tissue for extended periods of time. The new design provides the ability to displace sites, located at the tip of needles, away from the probe shank after implantation using microsprings. The sites record from tissue that is more viable and less impaired by the presence and implantation of the shank. Key technologies are presented that make this approach easily realizable within reasonable constrains. Silicon probes with 340 μm maximum width at the tip and 2 mm length were fabricated as mechanical test structures that have sufficient in-plane space to connect 6 sites, arbitrarily distributed across 1 mm along the shank. The springs are designed such that dipping into water / 0.4% heated agar (for 3 μm / 5 μm wide springs, respectively) retracts them, and bio-dissolvable coatings such as water, sugar and agar lock and release them. Insertion tests show that the fine needles withstand implantation and that the springs displace the comb more than 100 μm through brain surrogate after implantation.