Chemical Forums
Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: clayfulk on August 23, 2016, 02:37:45 PM
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Hey internet. I am in search of a material that acts as a hydrophobic/hydrophilic switch when electricity is applied. Most desirable properties would be corrosion resistance, longevity, and minimal electrical input to cause switch in properties.
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Lets say there was a material that I could put a water drop on. Then one section of the material I could apply a voltage and it would repel/attract water causing the water drop to move to another section of the material. Obviously the greatest potential would be to have the material able to go from hydrophilic to hydrophobic. The water drop would move from phobic to philic and then I could change which section is hydrophilic vs hydrophobic using applied voltage. This would allow me to move the water drop around on a surface. Is there a material that has this ability or something close?
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I like your example, I couldn't have come up with it on my own. That's a clever way of doing it, if it works. Microfabricating it, onto a substrate, which could be charged locally, would be an additional challenge.
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It looks fun, but I fear that voltage in water will produce H+ and OH- that poison your field-sensitive molecules. Also, water will reduce the electrostatic force exerted on the flexible molecule, down to zero if water is the more polar species.
Maybe you could just attract the droplet electrostatically. I'd use AC field through an insulator. Just water's permittivity would let attract it. Long ago I used XY plotters that held the paper sheet with two interleaved electrodes and an electric field, this was very effective. It may need water pure enough to limit heating, and a frequency high enough: for a given purity, compare the conductivity with the capacitance hence susceptance.
You could try with a printed circuit, the epoxy against water, the printed electrodes dry. Just spray some teflon, or glue a teflon film, to remove unprovoked wetting.
Or try to vibrate the substrate with piezo actuators where the droplet shall not stay.