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Microelectrode arrays (MEAs) are state-of-the-art devices for extracellular recording and stimulation on biological tissue. Furthermore, they are a relevant tool for the development of biomedical applications like retina, cochlear and motor prostheses, cardiac pacemakers and drug screening. Hence, research on functional cell-sensor interfaces, as well as the development of new surface structures and modifications for improved electrode characteristics, is a vivid and well established field. However, combining single-cell resolution with sufficient signal coupling remains challenging due to poor cell-electrode sealing. Furthermore, electrodes with diameters below 20 µm often suffer from a high electrical impedance affecting the noise during voltage recordings. In this study, we report on a nanocavity sensor array for voltage-controlled stimulation and extracellular action potential recordings on cellular networks. Nanocavity devices combine the advantages of low-impedance electrodes with small cell-chip interfaces, preserving a high spatial resolution for recording and stimulation. A reservoir between opening aperture and electrode is provided, allowing the cell to access the structure for a tight cell-sensor sealing. We present the well-controlled fabrication process and the effect of cavity formation and electrode patterning on the sensor's impedance. Further, we demonstrate reliable voltage-controlled stimulation using nanostructured cavity devices by capturing the pacemaker of an HL-1 cell network.

Nanocavity sensor arrays are powerful devices for parallel extracellular recordings of action potentials from cell networks. The sensors combine a high spatial resolution and seal resistance between cell and electrode with low electrode impedances, allowing low-noise electrophysiological measurements of individual cells in a network without the use of CMOS technology. In this paper, we present a new protocol for the simple fabrication of nanocavity sensors, which enables easy modification of standard microelectrode arrays. Our approach enables processing of devices with improved sensor characteristics and flexibility regarding electrode area and aperture size with minimal effort. We characterize the sensors by impedance spectroscopy and demonstrate their applicability by recording action potentials of individual cardiomyocyte-like cells growing in a network on the chip surface.