Vertically aligned carbon nanofiber electrode arrays
In a collaboration with Dr. M. Nance Ericson and Mr. Tim McKnight at Oak Ridge National Laboratory, we reported recording spontaneous and evoked neural electrical activity with a novel microelectrode array fabricated from vertically aligned carbon nanofibers (Yu et al., 2007). Our recordings were a significant achievement because they were a first critical step in measuring both electrical and neurochemical levels in a high-density multi-electrode array format. The extension to dual mode recordings in an MEA format is a significant development for studying the pathobiology of TBI because it is hypothesized that disrupted glutamate signaling plays a central role. With this new technology, we will be able to directly measure local glutamate concentrations simultaneously with electrical activity.
Stretchable microelectrode arrays
A second novel MEA technology that we are developing in collaboration with Dr. Sigurd Wagner (Electrical Engineering, Princeton University) is the stretchable microelectrode array (SMEA). SMEA are constructed from nanometer thick gold conductors on a stretchable silicone substrate. They possess the unusual ability to remain conductive while being stretched up to 12% biaxially and recover conductivity after being stretched up to 30% biaxially, making them compatible with my in vitro model of TBI (Yu et al., 2009). We have shown that the electrodes stretch with the tissue and remain in the same relative positions, which is significant for two reasons. First, sterility is maintained during recording so that the temporal progression of changes in electrophysiology can be quantified starting within a minute after injury. Second, because sterility is maintained, the pre-injury electrophysiological activity serves as an internal control for normalizing post-injury changes. Neither of these advantages can be achieved with commercially available MEA. We are now using these arrays to understand mechanically-induced changes in neuronal network function.