A team of Bioengineers led by Ozgur Sahin at Columbia University recently created most probably the world’s first engine which is able to run on water evaporation at room temperature as reported in the journal “Nature Communications”. It is mentioned that by only using a puddle of resting water, it can light up LEDs or even drive a miniature car. The better news is that it will cost less than $5 to make.
The most important part of the engine is a new material which is called HYDRAs (Hygroscopy-driven Artificial Muscles). The material is made from thin, muscle-like plastic bands that contract when it is dry and expand when it is humid. It is also able to response even to a tiny amount of moisture, it is able to contract and expand for more than a million times and almost degradable type of material. On top of that, it is also can expand up to four times of its original length. As the material expand and contract, it will create energy and thus it can be used to do some action as specified.
How does it work? The engine is placed over a puddle of room temperature water in a small closure. As the water evaporates, the closure will definitely become more humid and thus it triggers the HYDRA strips to expand. As they expand, they will pull a cord which is attached to a small electromagnetic generator and thus converting this movement into energy. At the same time, the strips will also pull open a set of four shutters on top of the engine releasing the humid air. As the humidity inside the closure drops, it the strips will contract and thus close the shutters. The process will repeat.
As for now the evaporation engine is considered as a proof of concept. For it to be able to be implemented for public use, it is still a far way to go.