Solar panels could be made from rows of tiny artificial sunflowers, which automatically bend towards light. Scientists in the U.S. have created an artificial sunflower less than 0.04 inches wide that can bend towards a light source and harvest solar energy.
Each artificial sunflower, known as a SunBOT, consists of a stem made of a material that reacts to light and an energy harvesting “flower” at the top, which is made from a standard light-absorbing material commonly used in solar cells. Each SunBOT is less than 1 millimetre wide. The flowers, dubbed SunBOTs, were found to be about 400 percent more efficient than comparable devices that are stationary, making them a promising technology for solar power—potentially even as a power source for solar-based spaceships.
When part of a SunBOT’s stem is exposed to light, it heats up and shrinks. This causes the stem to bend and point the artificial flower towards the light. The stem stops bending once SunBOT is aligned with the light because the bending creates a shadow that allows the material to cool down and stop shrinking.
The team, led by researchers from the University of California, Los Angeles, were looking to improve the efficiency of solar cells by emulating a feature of nature—phototropism. This is where a plant orientates itself to face the sun, optimizing the amount of energy it can get. Ximin He at the University of California, Los Angeles, and her colleagues tested the stems by building a panel of SunBOTs, with and without the bendy material. The team found that the panel of bendy-stemmed SunBOTs was able to harvest up to 400 per cent more solar energy.
“Almost everyone working in the field of responsive or smart materials gets inspiration from nature,” says Albert Schenning at Eindhoven University of Technology in the Netherlands, who wasn’t involved with the work. This is a good proof of principle, he says.
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