American scientists have learned to extract electricity from moisture in the air

As Arthur Clarke said, any sufficiently advanced technology is indistinguishable from magic. American scientists have clearly proved this postulate. Pretty simple on the face of it, it was able to extract electricity literally from the air.

A group of researchers from the Massachusetts University of Technology in Amherst (not to be confused with MIT) published an article in the journal Nature, which reported an interesting invention. The small device created by the scientists with sides of 1×2 cm was able to extract electric current from the surrounding humidity in the air. The device generated current for hours and was restored for further work after a short break.

The electricity generating element is a thin film 7 µm thick. But this is an unusual film. The film consists of nanometer-thick protein threads. These yarns are produced by the life activity of the Geobacter sulfurreducens bacteria. These are interesting bacteria. They produce reagents that allow the recovery of metals.

There are quite a few layers of protein filaments in the 7 micron film. Naturally, the entire thickness of the film is porous and able to absorb moisture from the surrounding air. Thus the bottom electrode occupies all area under a generating element, and the top closes only a small area on a film surface.

Due to the absorption of moisture from the air in the thickness of the film, a difference in humidity is created - a gradient is created in the direction of the lower electrode. Due to water molecules ionization processes begin on the surface of protein threads, which in turn leads to the appearance of mobile protons in the film - charge carriers. Since the humidity of the film (its gradient) changes from one electrode to another, there is also a gradient of charge carriers (protons) and, as a consequence, when the electrodes close or in case of connection of the load in the system, an electric current starts to flow.

The experiment has shown that the generator produces 0.5 V without load. The achieved current density was 17 µA per cm2. By connecting 17 such generators in series and connecting a capacitor to it as a balance, scientists were able to power a small screen. In this condition the circuit generated electricity for 20 hours, during which the voltage dropped by 30%. After an interruption of 5 hours, the contacts voltage was back to the original value.

The researchers believe that this invention can lead to power supplies for portable electronics or medical devices. Wet air is everywhere, even in the Sahara desert. And nothing else is needed to run the proposed generator.

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