How do ions and water interact at the atomic level in nanochannels grafted with polymer brushes using all-atom molecular dynamics simulations? Siddhartha Das of the University of Maryland and his team are working on answering this question.
News|Videos|October 16, 2026
The Electroslippage Effect: Generating Energy While Enhancing Flow in Brush-Grafted Nanochannels
In this SciX interview segment, Siddhartha Das explains how his group’s simulations revealed a nanochannel scenario that produces energy and boosts flow at the same time. This overturns the classical electroviscous trade-off without breaking the laws of thermodynamics.
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In this segment of his
To set up the concept, Das revisits the classical electroviscous effect. When a pressure-driven flow passes through a nanochannel with charged walls, it carries ions unevenly downstream, creating an ion imbalance between the two ends of the channel. That imbalance produces a streaming electric field, which in turn drives an induced electroosmotic flow opposing the pressure-driven flow. The net result is a reduced flow rate. Researchers who wish to capture this reduction without modeling the induced flow treat the liquid as if it has become more viscous, hence the name. Because an electric field is generated, the process also yields energy, so the classical trade-off is energy gained at the cost of flow lost.
Das’s simulations show a different outcome. The streaming field still points in the same direction as in the classical case. However, as his group found earlier, the electroosmotic flow in their system is driven by ions carrying the same sign as the charged wall. As a result, the induced flow runs with the pressure-driven flow instead of against it. The channel therefore generates energy while its overall flow rate increases, which Das describes as a win-win scenario.
He stresses that this does not violate the second law of thermodynamics. The additional energy comes from the dynamics of the brushes in the channel and the way they shape the ion distribution, a factor that is absent from classical electroviscous treatments.
Das recalls the result as a eureka moment. Needing a name for it, he chose “electroslippage” as a deliberate counterpart to “electroviscous.” Where viscous implies flow that is slowed, slippage suggests flow that moves faster, much as a person who slips on the ground speeds up before falling.
Further Reading
(1) Das, S.; Workman, Jr., J.; Wetzel, W. Siddhartha Das Discusses Electroosmosis in Soft Nanochannels at SciX 2026. Spectroscopy Online, 2026.
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