Scientists at Harvard University have developed a type of material that can be programmed to move in response to various stimuli, including light. One possible application, says the group, could be in solar panels with integrated microstructures that track the sun without any energy input.
Scientists at Harvard University’s Wyss Institute for Biologically Inspired Engineering and the John A. Paulson School of Engineering and Applied Sciences (SEAS) have created a material known as a liquid crystal elastomer (LCE), which they say can be programmed to move in response to stimuli.
One application that could be possible thanks to this discovery is the creation of a material designed to move in response to light. A microstructure built from such a material, the researchers say, could be integrated into a solar panel, allowing it to track the sun across the sky without any extra energy input.
The researchers were inspired to create such a material by observing similar functions seen in nature, for example the hair-like structures, or ‘setae’ on the bottom of a gecko’s feet, which possess a highly flexible composition to allow the creature to grip on to so many different surfaces.
The LCEs, described in the paper Multiresponsive polymeric microstructures with encoded predetermined and self-regulated deformability, published in the journal Proceedings of the National Academy of Sciences of the USA, can deform and change shape in response to heat, light and humidity, depending on their specific chemical and material properties. By exposing the precursor materials to a magnetic field as the LCE was synthesized, the researchers found that they could dictate the way in which the shape would deform when heated, and have it return to its initial shape at ambient temperature.
LCEs deform in response to heat, and the shape they deform to can be determined by exposing them to different magnetic fields during formation, according to Harvard’s Wyss Institute. Image: Wyss Institute at Harvard University
The autonomously tracking solar panel idea put forth by the Harvard team is based on another type of LCE, which was programmed to reconfigure itself in response to light. “When the structure was illuminated from a certain direction, the side facing the light contracted, causing the entire shape to bend toward the light,” the researchers explain, adding, “This type of self-regulated motion allows LCEs to deform in response to their environment and continuously reorient themselves to autonomously follow the light.”
The researchers also identify various other possible applications, including encryption, robotics and adhesive materials. And the lab expects to discover uses in an even broader range of fields as its work and understanding of LCES continues to improve.
“Asking fundamental questions about how Nature works and whether it is possible to replicate biological structures and processes in the lab is at the core of the Wyss Institute’s values,” says the institutes founding director Donald Ingber. “[This] can often lead to innovations that not only match Nature’s abilities, but improve on them to create new materials and devices that would not exist otherwise.”