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Tech

MIT Engineers Make Water Boil With the 'Flip of a Switch'

It's possible to speed the whole process along with a bit of current and dish detergent.
Image: MIT

There's something to the old idiom that a watched pot never boils. You, the impatient or perhaps just hungry water boiler are at the mercy of atmospheric pressure, thermal conduction, the dynamics of cavitation, and your own attention span. There's not much that can be done to speed the whole thing up beyond a couple shakes of salt, and it's best to just walk away and let the thing happen.

Of course, boiling is not some random event. It's a function of pressure and, usually, heat. You could come up a with a pretty good estimate of when exactly your pot is going to boil, assuming some basic pieces of information, but you wouldn't be able to do much to control it.

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As it turns out, the boiling of water can be manipulated quite easily with electricity. The MIT group featured in the below above did just that in experiments described in the journal Nature Communications: By passing current through a plate and then changing its polarization, it was possible to "seed" the formation of bubbles, giving the process a solid head-start.

The set-up requires one cheat. The water needs an additional surfactant to be mixed in—a dish detergent, basically. So it's soapy water.

The surfactant molecules are able to hold an electric charge, and by flipping the current back and forth in the metal plate, the researchers were able to cause the plate to become hydrophilic and hydrophobic. If the plate is hydrophobic, then the boiling process gets a boost. The water "nucleates" around tiny irregularities in the plate's surface and, hey, check it out, bubbles. If the plate is in a hydrophilic (water attractive) state, the water is more inclined to hang around the plate.

You can sort of imagine the plate and its attractive and repellent properties adding or subtracting pressure from the water, or from the force the water exerts on its environment (the air above it). Obviously, the water with the hydrophobic plate is going to push against the air more and boil quicker.

This technology might even prove to be useful. "Overall, temporal control of boiling would be advantageous for non-steady-state applications such as dispatchable power stations, electronics cooling, distributed power, or microfluidic actuators," the MIT group concludes.