Presenter: Youjoung Kim
Advisors: Jeffrey Capadona & Allison Hess-Dunning
Abstract: Spinal cord injury is a devastating condition for patients, resulting in para or tetraplegia. Brain computer interfacing (BCI) offer a way for paralyzed patients to regain movement, thus improving their quality of life. Penetrating implantable electrodes that are able to obtain single cell resolution such as Intracortical microelectrodes (IME) are necessary components in BCI. Unfortunately, these IMEs demonstrate steady decline in performance over time ultimately resulting in device failure. Chronic neuroinflammation has been shown to be a major contributor of device failure, exacerbated by oxidative stress and micromotion. Current industry standard devices rely on stiff substrates, resulting in high differential strain between the device and brain tissue that exacerbate the effects of micromotion. Additionally, reactive oxygen species (ROS) generated by activated immune cells such as microglia and macrophages cause damage to the device material and to the cells in the vicinity, leading to neuronal death. A device has been developed that aims to decrease differential strain by utilizing a mechanically adaptive polymer nanocomposite material comprised of tunicate cellulose nanocrystals (tCNC) in a polyvinyl acetate (PVAc) substrate, that is stiff when dry to facilitate insertion, but becomes soft when wet. Additionally microfluidic channels were integrated into the device for antioxidant drug delivery to reduce oxidative stress. The fabrication method has been optimized to produce devices that reliably and chronically deliver drug solutions. Devices underwent benchtop testing to validate function and implemented in pilot in vivo studies to determine an optimal microfluidic design. The chosen microfluidic design was used in a full in vivo study that aimed to determine the extent of inflammation mitigation achieved by soft materials, antioxidant delivery, and their combination as compared to industry standard silicon single shank probes. Bulk gene analysis was used to determine the extent of inflammation.