In vitro verification of a 3-D regenerative neural interface design: examination of neurite growth and electrical properties within a bifurcating microchannel structure

Toward the development of neuroprosthesis, we propose a 3-D regenerative neural interface design for connecting with the peripheral nervous system. This approach relies on bifurcating microstructures to achieve defasciculated ingrowth patterns and, consequently, high selectivity. In vitro studies were performed to validate this design by showing that fasciculation during nerve regeneration can be influenced by providing a scaffold to guide growth appropriately. With this approach, neurites can be separated from one another and guided toward specific electrode sites to create a highly selective interface. The neurite separation characteristics were examined for smaller microchannel structures (2.5 and 5 ¿m wide) and larger microchannels (10 and 20 ¿m wide), with smaller microchannels shown to be statistically more effective at initiating separation. Electrodes incorporated at different locations within the microchannels allowed for the recording and tracking of action potential propagation. Microchannel size was also found to play an important role in this regard, with smaller microchannels amplifying the recordable extracellular signal; a twofold increase in the signal to noise ratio was found for 5 ¿m wide microchannels.