Polymer SunBOTs Imitate Sunflowers to Create Maximum Solar Energy

A lot of living organisms exhibit a phenomenon called phototropism, in which they follow light sources to remain aligned with them. Young sunflower plants, for example, shift their stems’ positions during the day to ensure that they soak up the optimum amount of sunlight while the earth beneath them moves in relation to the sun. Then they shift back during the nighttime. Older sunflowers just stay in the same position.

But now, a team of scientists from UCLA and Arizona State University has developed a polymer that mimics sunflowers’ phototropism. As described in this study published in the journal Nature Nanotechnology in November 2019, the sunflower-like biomimetic omnidirectional tracker is called the SunBOT.

The device, which is just 0.039 inches (1 millimeter) in diameter, contains a nanomaterial that converts light into heat causing it to shrink as a result. This shrinkage propels the device to bend toward the light. As the shaded underside of the stem cools, it stops the device’s movements in a position that’s optimally oriented to absorb light. The SunBOT will shift slightly during the day as the angle of sunlight changes.

That ability to mimic an actual sunflower enables the SunBOT the harvest 90 percent of the energy from sunlight when it’s angled 75 degrees away from a perpendicular line to the surface, compared to just 24 percent achieved by stationary solar panels, UCLA material science and engineering assistant professor Ximin He told the Daily Bruin, the UCLA student newspaper.

Professor He explained that the new technology has the potential to double the amount of energy that a stationary solar panel can collect, which will make future solar energy much more readily available.