High-resolution neurostimulation and optogenetic electrophysiology with PEDOT:PSS-coated graphene

Micron-sized graphene electrodes hold promise in neurointerfacing for their outstanding mechanical, electrical, and optical properties. To understand the neural heterogeneity, it will be essential to examine if graphene electrode arrays can scale down their pitch size and probe neural activity at cellular levels. Here we present a 28-μm pitched PEDOT:PSS-coated graphene microelectrode array (MEA) that achieves one order higher resolution than prior graphene MEAs in both neuro-stimulation and optogenetic electrophysiology. Our array features high yield (100 %), low-impedance (sub-100 kΩ), low light-induced artifact (sub-2 μV), and high charge-injection-capacity (> 1.31 mC/cm
²
), suggesting its possible use for high-precision multi-modal neurointerfacing.