February 1, 2020

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Surface-induced flow: A natural microscopic engine using infrared energy as fuel

May 8, 2020

Paper published May 8, 2020

link to journalfull text (PDF)






Fluid commonly flows in response to an external pressure gradient. However, when a tunnel-containing hydrogel is immersed in water, spontaneous flow occurs through the tunnel without any pressure gradient. We confirmed this flow in a wide range of plant- and animal-derived hydrogels. The flow appears to be driven by axial concentration gradients originating from surface activities of the tunnel wall. Those activities include (i) hydrogel-water interaction and (ii) material exchange across the tunnel boundary. Unlike pressure-driven flow, this surface-induced flow has two distinct features: incident infrared energy substantially increases flow velocity, and narrower tunnels generate faster flow. Thus, surface activities in hydrogel-lined tunnels may confer kinetic energy on the enclosed fluid, with infrared as an energy source.

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Gerald H. Pollack, PhD

Professor of Bioengineering - Box 355061

University of Washington

Seattle, WA 98195


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