There’s waterproof and then there’s the surface developed by engineers at the University of California San Diego. They’ve developed a surface so hydrophobic that it can actually be used to generate electrical voltage, turning seawater into 50 millivolts (or around 0.05 volts).
Electrical voltages can be generated by ions, atoms with an electrical charge, moving over a charged surface. As ions move quickly over a charged surface, they can create voltage, and the faster the ions move, the more voltage can be created.
Water can act as either an acid or a base filled with both hydrogen and hydroxide ions. The created surface holds a negative electrical charge, so when the positive ions in salt water move over the surface an electrical potential difference is created. That difference creates a voltage.
The surface, created by a team led by professor Prab Bandaru and grad student Bei Fan, is hydrophobic to the extent that not even water’s ions can slip through its surface. The surface is made up of a silicon substrate, also known as a silicon wafer. With this thin slice of silicon, the team etched tiny ridges into the surface and then filled those ridges with synthetic motor oil for lubrication.
“The reduced friction from this surface as well as the consequent electrical interactions helps to obtain significantly enhanced electrical voltage,” says Bandaru in a press statement.
Although it’s just a proof of concept, the idea becomes impressive when deployed on a much larger scale. There’s a lot of ocean water out there, and the team hopes that it could be used for energy harvesting methods through desalination plants. From ions to waves, there’s a lot of potential energy in the water that covers 70 percent of the planet, and these hydrophobic surfaces could help tap into that energy.