Somatosensory Map Following Stimulation of Rat Sciatic Nerve Using Polyimide Microfabricated Sieve Electrodes

Neural interfaces operate at the intersection of biology and electronics. Development of these interfaces has focused on making it possible to systematically extract intention from cortical activity, to actuate anything from prostheses to computer-assisted communication systems, primarily through invasive Brain-Computer Interfaces (BCIs). These technologies have matured at a rapid pace but impart challenges in chronic stability; and in the case of prostheses, true bi-directionality. Mobility can be restored in a patient using functional electrical stimulation or an artificial prosthesis, however, research has shown that lack of sensory feedback results in difficulties using the prosthesis leading to abandonment of the device. Peripheral nerve interfaces (PNIs) provide an alternative means to interacting with the brain and nervous system at a less invasive level than BCIs. PNIs maintain the benefit of interfacing a discrete neurological maps of sensory function required to make prostheses more amenable, as well as, less reliant on visual feedback. This dissertation studies the modeling, design, fabrication of the regenerating nerve microsieve electrode (μSE): a PNI exhibiting exceptional chronic stability, somatotopical selectivity, and the potential for true bidirectionality. This work also encompasses the usage of the macrosieve sieve electrode (MSE) to elicit somatosensory cortical responses in a rodent model. The MSE is a stable nerve interface that has demonstrated successful utilization in the context of efferent recruitment, but has never been observed in the context of afference. The results address the advantages of peripheral regenerative nerve interfaces over their cortical counterparts, the impact of sieve transparency in recruitment thresholds and selectivity, the importance of sieve transparency in the quality of regeneration and the ability to use functional electrical stimulation to provide somatosensory feedback