(Invited) Novel Three-Dimensional Fuzzy Graphene (3DFG)-Based Platform for Interrogation of Excitable Cells

Investigating and modulating electrical activity of cardiomyocytes and neurons is essential to understanding their physiology, regeneration of excitable cells/tissues, and treatment of various disorders. Recently, microelectrode arrays (MEAs) have gained tremendous popularity since they enable multi-site recordings at sub-msec temporal resolution, provide two-way interaction with cells i.e. recording and stimulation, and have well-established microfabrication methods. However, currently used planar MEAs are not able to record and stimulate at sub-cellular resolution due to significant increase in electrode impedance which reduces the signal-to-noise ratio (SNR) of recorded signal. Currently there is a need to (i) enable high density electrode arrays, (ii) provide high spatial resolution, and (iii) prevent averaging of signals from multiple cells. To address these needs, we have developed three-dimensional out-of-plane grown fuzzy graphene (3DFG)-based MEA. Out-of-plane growth of single-to-few layers of graphene flakes leverages graphene's outstanding surface-to-volume ratio. The high surface area leads to significant reduction in impedance, thus enabling electrical recordings with high SNR and development of ultra-microelectrode arrays to perform sub-cellular measurements. Furthermore, the high flake density of graphene in 3DFG lead to high photo-absorbance in UV-NIR range. This opens up avenues to enable photo-thermal stimulation of cells with high precision and sub-cellular resolution. Our presented approach would greatly impact our basic understanding of signal transduction in complex cellular assemblies. Furthermore, it would provide a platform for developing and screening of therapeutics, and treatment of various cardiac and neurological diseases.