BIOMEDICAL ENGINEERING

Intracortical microelectrodes embedded chronically in the cerebral cortex hold promise for using neural activity to restore motor function in individuals who have suffered from spinal cord injuries, stroke, limb amputation, or neural degenerative diseases. Unfortunately, the quality of the signal available through currently available neural interfaces usually degrades within a few months, making chronic applications challenging. While several methods have been investigated to increase the longevity of intracortical microelectrodes implanted in the cerebral cortex, this technology has rarely been applied to human patients due to an incomplete understanding of the mechanisms that lead to the inability to detect neural activity.
A potential limiting factor of current technology is the mechanical mismatch of the microelectrodes with the cortical tissue. While a high modulus microelectrode is advantageous during insertion, a chronically stiff microelectrode causes micro-motion, micro-damage, and chronic astrocytic response in the brain tissue. The primary objective of this research was to design stimulus-responsive, mechanically-dynamic polymer nanocomposites for the use as intracortical microelectrodes which offer both a rigid phase for ease of insertion, and a mechanically compliant phase to address chronic mechanical mismatch related limitations.
This seminar will discuss the design and implementation of bio-inspired polymer nanocomposites. This new class of mechanically-dynamic materials was modeled after the natural three-phase defense mechanism for the mechanical reinforcement of the skin of the sea cucumber, and reversibly displays over a 1000-fold contrast in moduli from rigid to compliant states. These chemo-responsive mechani¬cally-dynamic nanocomposites are currently being investigated in an in vivo rat model to evaluate the tissue response as well as chronic inflammatory response for their potential to serve as ‘smart’ substrates for intracortical microelectrodes.
We are also interested in understanding the cell-mediated biochemical events which play a significant role in neural degeneration surrounding implanted intracortical electrodes, and will discuss future directions focusing on the attenuation of these responses through materials-based therapies for the delivery of anti-inflammatory agents, and the immobilization of regulatory cell-adhesive peptides.

Host: Professor Dustin Tyler