Design of CMOS Neural Probes Utilizing Micro-coil Magnetic Neurostimulation

172 pagesNeural prostheses that stimulate the neocortex utilizing electrical stimulation via implantable electrodes have been used to treat a wide range of neurological and psychological disorders. However, fundamental limitations of implantable electrodes have limited the prosthesis effectiveness as there remains concerns over their long-term stimulation efficacy and inability to create precise patterns of neural activity. Latest developments in micro-magnetic technology have shown that magnetic stimulation from micro-coil-based neural probes is capable of modulating neural behavior while circumventing the limitations of implantable electrodes. This is due to the induced electric fields from magnetic stimulation being spatially asymmetric, avoiding the simultaneous stimulation of passing axons, as well magnetic fields having high permeability to biological substances, allowing for complete device encapsulation. While these devices have been shown to modulate neural activity in both in vitro and in vivo experiments, the lack of reconfigurable hardware on the probe fixes the location of the neurostimulation sites post-implantation. This works explores how co-designing CMOS circuitry, micro-coil design, and nanofabrication processing can be used to fabricate the next generation of micro-coil-based neural probes, capable of spatially programmable micro-magnetic neurostimulation