Your heart beats, your neurons fire, your muscles contract. The human body runs on electricity, but not all of it comes from the usual suspects like ion channels and sodium-potassium pumps. New theoretical work suggests that cell membranes themselves, those thin molecular sheets that wrap every living cell, may be harvesting power from their own ceaseless motion.
Researchers at the University of Houston have modeled how biological membranes convert mechanical fluctuations into real voltage. The mechanism relies on flexoelectricity, a property where bending a material generates electric polarization. When proteins embedded in the membrane consume ATP and shift position, they inject energy that makes the membrane ripple. Those ripples, in turn, produce electrical signals that can reach 90 millivolts under realistic cellular conditions, comparable to the voltage changes during a neuron’s action potential.
The findings, published December 16 in PNAS Nexus, offer a new physical basis for understanding how cells generate bioelectricity. Lead researcher Pradeep Sharma and colleagues Pratik Khandagale and Liping Liu built a framework showing that membranes aren’t just passive barriers. They’re active electrical generators, powered by the molecular noise of life itself.
Why Thermal Jiggle Isn’t Enough
Cell membranes undulate constantly at the nanoscale. At thermal equilibrium, these motions are random and reversible, which means they can’t do useful work. Classical thermodynamics forbids extracting energy from pure thermal noise.
Living cells break that rule. Proteins don’t sit still. They consume ATP, change shape, exert forces. These active processes generate fluctuations that are correlated in time and directionally biased, a departure from equilibrium that opens the door to energy harvesting.
The team’s nonequilibrium statistical mechanics model couples membrane bending to voltage through flexoelectricity. When active protein forces drive curvature changes, the membrane’s electrical polarization shifts. The result is a transmembrane voltage that emerges on millisecond timescales, matching the characteristic timing of neuronal firing.
According to the authors, “We show that these active fluctuations, when coupled with the universal electromechanical property of flexoelectricity, can generate transmembrane voltages and even drive ion transport.” The predicted voltage isn’t a marginal effect. It’s large, fast, and directional.
From Ion Pumps to Action Potentials
The consequences extend beyond voltage generation. The model predicts that active membrane fluctuations could power ion transport against electrochemical gradients, effectively turning the membrane into a pump without requiring dedicated molecular motors. Ion flow direction depends on the membrane’s elasticity and dielectric properties, offering a physical explanation for how cells control movement of charged particles through mechanical activity alone.
The work also provides a lens on neuronal signaling. The nonlinear voltage rise produced by active fluctuations closely resembles action potential curves. This suggests flexoelectric effects could contribute to how neurons initiate electrical firing, linking membrane mechanics directly to sensory processes and neural computation.
“The mechanism provides a physical basis for understanding sensory processes, neuronal firing, energy harvesting in living cells, and may provide a potential link between brain neuron functioning and physically intelligent materials,” the researchers explain.
Flexoelectricity has already been implicated in hearing and touch. This study expands its relevance to active transport and bioelectric signaling across cell types. More broadly, it points to a unifying principle connecting membrane mechanics, electricity, and cellular function.
Looking ahead, the framework could be extended to multicellular systems. If active membrane fluctuations coordinate across tissues, they might explain collective bioelectric phenomena during development, regeneration, or brain activity. The work also opens doors for bio-inspired materials that harvest energy from internal molecular motion rather than external power sources, much like cells do naturally.
For now, the study offers a striking shift in perspective: living membranes don’t just respond to electricity. They generate it, drawing power from the restless molecular activity that defines life itself.
PNAS Nexus: 10.1093/pnasnexus/pgaf362
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