High-performance, Conformable, Stencil Fabricated Graphene μ-ECoG Array

To study the brain, there is a need for an easy-accessible neurosensing tool for performing brain recording in high spatiotemporal resolution. Most electrocorticography (ECoG) electrode arrays to date are based on microfabrication techniques, making them expensive and challenging to reconfigure for experiment-specific electrode designs. Here, we investigate a low-cost, liquid exfoliated two-dimensional graphene-based, flexible, 16 channel μ-ECoG electrode array implanted on the cortex in rodents for high-resolution neurophysiological recording and in vivo optical imaging. For the first time, a low-cost, mass-producible, stencil-based technique for fabricating an ECoG array is successfully developed where a flexible mask was crafted with a laser cutter that evades the use of expensive micromachining. The array was successfully implanted in mice maintaining an average surface impedance of 369 MΩ.μm2 at 1 kHz after 1 week of implantation, which is 4 times lower than the prior reports. We also present a direct comparison of the simultaneous recording in awake and anesthetized states, where the brain signals at the awake state demonstrated more complex signal characteristics. The device should pave the way towards fundamental studies on behaviors and disease models.