A novel electrophysiological device to simultaneously measure local field potential and spiking activity in neuronal cultures

A system at the critical point should exhibit scale invariance. In neuronal cultures, spikes are microscopic signals, requiring microelectrode arrays with small diameters for individual neuron resolution. In contrast, the local field potential (LFP) is considered a macroscopic signal, supposedly an average over local signals, and can be measured using electrode arrays with larger diameters. To facilitate simultaneous measurement of both spikes and LFP, we engineered a microelectrode array with varying interspacing between small and large electrodes on the Mind-in Vitro platform. This novel approach enables direct comparison of signals across different spatiotemporal scales, providing insights into the renormalization of electrophysiology within biological neuronal networks. Our approach provides a means to experimentally test the local averaging conjecture of the LFP activity.