Scientists are constantly trying to harness energy from everything – sunlight, wind, tides temperature and so on. Now scientists at the RIKEN institute and the University of Tokyo have developed a film, which uses the power of humidity. Researchers say this type of energy will be extremely useful for the development of the sustainable society.
This film is very interesting, because it reacts to tiny fluctuations in the ambient humidity. It curls up and straightens out autonomously when exposed to different levels of humidity and this difference can be extremely small. However, irradiation in ultraviolet light changes film’s ability to absorb moisture and it can even jump into the air as it moves. Interestingly, this film was created accidentally when scientists placed guanidinium carbonate into a high-temperature oven and found that besides forming the usual powdery substance it also formed this yellow carbon nitrite polymer film.
Team of scientists quickly discovered that this film curls up reacting to tiny fluctuations in the ambient humidity – so tiny, that they are virtually undetectable. Films curled up so quickly too – the change took just 50 milliseconds. It was clear that the film can absorb moisture, therefore scientists weighed the film and found that it can be 680 nanograms per 10 square millimetres heavier when it absorbed water. However, the most surprising characteristic of this process is the energy that this film produces when moving.
While curling up the film can jump up to a centimetre high – a height 10,000 times the thickness of the film. Also, the film is very durable. Scientists made one film bend and straighten for more than 10,000 times and could not detect any deterioration. Although this discovery is fairly new, scientists already had some fun with it. They covered one half of the film with gold, which stops water absorption and desorption. Then film could actually walk across the surface as half of the film was bending and unbending. Takuzo Aida, leader of the research team, said: “In the same way that a mechanical watch takes advantage of the natural movements of the wrist to gain energy, this film takes tiny fluctuations in the ambient humidity and transforms them into mechanical energy”.
It is a very interesting material. It is so tiny, yet can produce big amounts of energy from thin air. However, it will take a lot of time till any bigger devices can be developed using this film.