PROJECT SUMMARY/ABSTRACT: Action potentials are temporal changes of the electrical voltage across the cell membrane, which are crucial for the physiological function of excitable cells such as neurons and cardiomyocytes. In the human heart, cardiac action potentials coordinate the synchronous contraction and relaxation of billions of cardiomyocytes. The waveforms of intracellular action potentials reflect the coordination of a multitude of ion channels, some of which are affected by pharmaceutical drugs to collectively contribute toward proarrhythmic risks. The waveforms of intracellular action potentials also reflect the subtype such as atrial-, ventricular-, or nodal-like cardiomyocytes, or their maturation status. Measurements of intracellular action potentials are mostly performed by the patch clamp technique, which is accurate but invasive, one cell at a time, laborious, and requires specialized expertise. Due to its low throughput and invasive nature, patch clamp is not suitable for drug screening or functional characterization of human pluripotent stem cell derived cardiomyocytes. In the last decade, vertically-aligned and solid-state nanoelectrode arrays (NEAs) have emerged as promising tools with the potential of achieving parallelizable and minimally invasive cardiac AP recording from monolayers of stem-cell-derived cardiomyocytes. However, despite the significant progress and the strong interest, the NEA technology has largely been confined to research groups that develop the technologies, instead of being broadly adopted by the research community. We identified several critical challenges that have hindered such effort. In this proposal, through the partnership between an academic lab and a startup company, we aim to overcome these challenges and develop a robust electrophysiological tool that enables reliable, scalable, and long-term intracellular recording of cardiomyocytes. The goal of this proposal aims to transition the NEA technology from a demonstration of possibility to a status useful to end-users.