A recent report, published in the journal Nature Communications by MIT postdoc Nenad Miljkovic, details the completely unexpected phenomenon discovered by MIT researchers that tiny water droplets which form on a superhydrophobic surface and then jump away from the surface, actually carry an electrical charge.
They believe that further research and experimentation could lead to the development of a new way of drawing power from the atmosphere itself.
Miljkovic explained that in previous experiments the team had found that under certain conditions the water droplets forming on the superhydrophobic surface due to simple condensation was jumping away rather than just sliding down the surface due to gravity.
Droplets jumping off a superhydrophobic surface. (MIT News)
They then performed more tests, and “found that when these droplets jump, through analysis of high-speed video, we saw that they repel one another mid-flight. Previous studies have shown no such effect. When we first saw that, we were intrigued.”
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The researchers then designed a series of experiments that would test the reasons for why the droplets were repelling each other after they had left the surface. By using a charged electrode they found that a positive charge would repel the droplets, and cause them to repel each other, and that a negatively charged electrode would attract the droplets. This allowed them to surmise that the droplets created a net positive electrical charge when they left the surface.
Jonathan Boreyko, a postdoc at Oak Ridge National Laboratory, said that “the fact that the jumping droplets exhibit a net charge was completely unknown until this report … It is my impression that this work is of very high quality and will have a large impact on the rapidly evolving field of phase-change heat transfer on nanostructured surfaces.”
Miljkovic hopes that by positioning two metal plates in parallel, and using one plate to form the drops and have them jump off it and the other plate receiving the droplets, you could generate a small amount of power from the natural condensation in the ambient air. She explained that “you just need a cold surface in a moist environment. We’re working on demonstrating this concept.”
By. Joao Peixe of Oilprice.com
Joao is a writer for Oilprice.com