Flexoelectricity and the fluctuations of (active) living cells: Implications for energy harvesting, ion transport, and neuronal activity.

Biological membranes universally exhibit flexoelectricity, a form of electromechanical coupling in which membrane curvature induces electric polarization. This phenomenon enables the conversion of mechanical deformations into electrical signals and plays a central role in sensory processes such as hearing. Flexoelectricity can also ostensibly provide a facile route for energy harvesting via membrane flexure, and, in principle, enable useful work (e.g. as an ionic pump). While all cell membranes undergo noticeable thermal fluctuations at physiological temperatures, equilibrium fluctuations alone cannot yield net harvested energy. In this work, we recognize that cells are inherently active, living systems, driven far from equilibrium by processes such as protein dynamics and ATP hydrolysis, and develop a theoretical framework to investigate the flexoelectric response of actively fluctuating membranes. Our results reveal that activity can significantly amplify transmembrane voltage and polarization, suggesting a physical mechanism for energy harvesting and directed ion transport in living cells. We highlight potential applications of our findings in the context of ion transport and neuronal action potentials.