High-Resolution Graphene-Based Flexible Electrode Array

Biomedical electronics especially that detect brain’s electrical activity are essential to brain study including functional mapping or lesion mapping. Nowadays, as study has been advanced, demand for high-resolution devices that can accurately obtain data for precise analysis has increased. However, conventional electrocorticogram (ECoG) devices could just provide low-resolution data due to their wide spacing and poor electrochemical property with high impedance causing low signal-to-noise ratio (SNR)<br/>Here, we propose a high-resolution electrode array. We utilized graphene and thin gold film to form electrodes and encapsulated with Parylene C which are all biocompatible materials. The electrodes show low impedance of 42.4 kΩ and 103.7 kΩ at 1 kHz for size of 100 μm×100 μm and 60 µm×60 µm, respectively. The low impedance enables the electrodes to detect brain signal better as compared to conventional gold electrodes. Finally, the optimum spacing and size of the electrodes to get high-resolution data was established and tested on a rat. The electrodes were conformally attached to somatosensory cortex and response to body stimulation in the form of distinctive spikes were recorded. Peak-to-peak voltages of channels showing responses were quantified and classified according to their amplitudes. As a result, we have successfully identified boundary where the response occurs in a resolution of 50μm, indicating high-resolution ECoG signal. We believe that our high-resolution electrode array will lead us toward advanced study and better understanding of brain.