Speaker
Description
New developments in neuroscience have driven rapid advancements in implantable devices at the brain-machine interface for both research and clinical applications. One such device is the Neuropixels probe, used currently in research and pre-clinical testing, which collects high-density, time-resolved neural impedance recordings across multiple brain regions. However, these implants are limited by biocompatibility mismatches at the machine-tissue interface. The long-term implantation of these devices elicits the host's immune response to reject the foreign object, leading to glial scarring and signal degradation. We investigate a highly tunable biomimetic interface approach through layer-by-layer (LBL) charged polymer method of assembly. In collaboration with the Montreal Neurological Institute, we are developing a naturally derived polycation, known as DPGA which promotes favorable neuron–surface interactions by bio-camouflaging the implant surface. Due to the optical transparency of the molecular layers, a key challenge is the direct characterization of the coating on the probe. To address this, we are developing a surrogate technique, based on biocompatible dyes, to characterize the presence of the bio-camouflage while retaining the electrical integrity Neuropixels probe. Optical spectroscopy and ellipsometry are used to assess film thickness, packing density, and uniformity. Dye-uptake measurements show increase in uptake capacity with 8 bilayer films showing approximately sevenfold higher maximum absorbance than single bilayer films; And a reduction in dye uptake kinetics were increasing the number of bilayers from 1 to 8 reduces the effective uptake rate constant (k)by two orders of magnitude, from 〖~10〗^(-2 ) s^(-1 ) to 〖~10〗^(-4) s^(-1). In vitro cell studies are also discussed to evaluate biological responses to the bio-camouflage. Results suggest an optimal threshold of approximately four bilayers under physiological conditions. Beyond this threshold, increased coating thickness is associated with reduced cell adhesion. Finally, impedance and SNR measurements are being investigated to test bio-camouflaging effects on the electrical performance of the probe.
| Keyword-1 | Brain–machine interfaces |
|---|---|
| Keyword-2 | Neural probes |
| Keyword-3 | Layer-by-layer assembly |