Conductive electrospun and micro-stereolithographically produced porous scaffolds as potential neural interface materials

Our overall intent is to develop improved electrically active prosthetic devices to allow interactions between regenerated nerve fibers (axons) and external electronics. To allow for infiltration of axons, these devices must be highly porous. Additionally, they must exhibit selective and structured conductivity to allow the connection of electrode sites with external circuitry with tunable electrical properties that enable the transmission of neural signals through physical connections to external circuitry (e.g. through attached wires.) The chosen material must be biocompatible with minimal irresolvable inflammatory response to allow intimate contact with regenerated nerve tissue and mechanically compatible with the surrounding nervous tissue. We have utilized electrospinning and projection lithography as tools to create conductive, porous networks of non-woven biocompatible fibers in order to meet the materials requirements for the neural interface. The biocompatible fibers were based on the known biocompatible material poly(dimethyl siloxane) (PDMS) as well as a newer biomaterial material developed in our laboratories, poly(butylene fumarate) (PBF). Both of the polymers cannot be electrospun using conventional electrospinning techniques due to their low glass transition temperatures, so in situ crosslinking methodologies were developed to facilitate micro- and nano-fiber formation during electrospinning. The conductivity of the electrospun fiber mats was controlled by varying the loading with multi-walled carbon nanotubes (MWNTs).