Stretchable microelectrode arrays--a tool for discovering mechanisms of functional deficits underlying traumatic brain injury and interfacing neurons with neuroprosthetics.

Traumatic brain injury (TBI) can be caused by motor vehicle accidents, falls and firearms. TBI can result in major neurological dysfunction such as chronic seizures and memory disturbances. To discover mechanisms of functional deficits underlying TBI, we developed a stretchable microelectrode array (SMEA),which can be used for continuous recording of neuronal function, pre-, during, and post-stretch injury. TheSMEA was fabricated on a polydimethylsiloxane (PDMS)substrate with stretchable, 100 pm wide, 25 nm thick gold electrodes patterned there on [1]. The electrodes were encapsulated with a 10-20 microm thick, photo-patternable PDMS insulation layer. Previous biocompatibility tests showed no overt necrosis or cell death caused by the SMEAs after 2 weeks in culture [2]. The electrical performance of the SMEAs was tested in electrophysiological saline solution before, during and after biaxial stretching. The results showed that the electrode impedance increased with the strain to reach 800 kL at 8.5% strain and then recovered to 10 kil after relaxation. The working noise level remained below 20 pV pp during the whole process. New methodologiesf or improving the patterning of the encapsulation layer were tested on gold electrode arrays supported on glass. With these prototype arrays, robust population spikes were recorded from organotypic hippocampal slice cultures of brain tissue. Additionally, seizure-like activity induced with 1 mM bicuculline was also recorded. Our results demonstrate that the prototype arrays have good electrical performance compatible with existing multielectrode array systems. They also indicate the ability to record neuronal activity from hippocampal slices. This novel technology will enable new studies to understand injury mechanisms leading to post-traumatic neuronal dysfunction.