Informal NB & CNS Seminar | Tansel Baran Yasar - Tuesday, November 22, 2022 - 3:30 pm
Tuesday, November 22, 2022
Tansel Baran Yasar
"Ultra-flexible low-impedance electrode arrays for chronic, large-scale and stable recordings of single-unit activity from multiple brain areas in freely moving rodents"
While the number of channels in the state-of-the-art in vivo electrophysiology systems are rapidly increasing, these technologies generally use stiff materials. The mechanical mismatch between these probes and the brain causes damage to the brain tissue, limiting the longevity and quality of recordings. To address this challenge, we have developed ultra-flexible high-density intracortical and surface microelectrode arrays. In the intracortical arrays, each channel is mechanically independent to provide maximal compliance with the brain tissue—while also allowing to pack a high density of channels within a minimal footprint at each brain area, with 256 channels in total. During the fabrication of our devices, we robustly achieve 54±16 kOhm impedances for electrode pads with 13x13 µm2 surface area and 2.4 µm thickness. Thanks to our novel electrode geometry and insertion method, the intracortical electrode arrays can be delivered into multiple brain areas at arbitrary locations with practically no depth limitations at a speed of 12.5 µm/s.
In the case of intracortical arrays, we get stable recordings of single-unit activity on a time scale of several months to a year, while tracking putatively the same single units across months in some cases. Immunostaining of the brain slices shows no significant long-term damage to the brain tissue surrounding the electrodes. In the case of the surface arrays, we can record high quality uECoG signals as well as putative single-unit activity from the brain surface due to the high conformity with brain surface and the low electrode-tissue impedances. We are currently scaling up our electrode arrays and recording electronics to cover more brain areas with larger numbers of channels wirelessly for untethered recordings. In this talk, I will describe our methodology for the fabrication and surgical implantation of our electrode arrays, and present the results of our recordings from various animal models by using multiple generations of the surface and intracortical ultra-flexible microelectrode arrays.