Imagine a person on the ground piloting a drone in the air that uses energy from the laser beam and eliminates the need to carry a bulky onboard battery. This is the vision of a group of scientists from the Hayward Research Group at the University of Colorado at Boulder.

In a new study, researchers in the Department of Chemical and Biological Engineering have developed a new flexible photomechanical material that can convert light energy into mechanical work without heat or electricity, opening up innovative possibilities for energy-efficient wireless and remote-controlled systems. Its broad potential spans a variety of industries, including robotics, aerospace and biomedical engineering.

“We take the light energy, the man in the middle, so to speak, and convert it directly into mechanical deformation,” Professor Ryan Gayward said.

Hayward and his team describe the new material in a report published July 27. Nature Supplies.

The material consists of small organic crystals that begin to bend and lift objects under the influence of light. Research shows that these photomechanical materials offer a promising alternative to wired actuators, with the potential to control or operate robots or vehicles wirelessly. In addition, increasing the efficiency of direct light-to-work conversion makes it possible to avoid cumbersome temperature control systems as well as heavy electrical components.

The research contrasts with previous attempts involving delicate crystalline solids that change shape through a photochemical reaction but often crack when exposed to light and are difficult to convert into useful actuators.

“The interesting thing is that these new riders are much better than the ones we’ve had before. They respond quickly, last a long time and can lift heavy things.”

Hayward’s Lab’s innovative approach involves using small arrays of organic crystals within a polymer material that resembles a sponge because of its tiny holes. When crystals grow in the micron-sized pores of the polymer, their durability and energy production under the influence of light are greatly increased. Their flexibility and ease of molding make them versatile for a wide variety of applications.

The orientation of the crystals allows them to perform tasks under the influence of light, such as bending or lifting objects. When the material deforms with a bound load, it acts as a motor or actuator and moves the load. Crystals can move objects much larger than themselves. For example, as seen in the image above, a sliver of 0.02 mg of crystals successfully lifts a 20 mg nylon ball 10,000 times its own mass.

CU Boulder researchers also include lead author Wenwen Xu, a former postdoctoral fellow in Hayward’s group (now at the Sichuan University-Pittsburgh Institute), and Hantao Zhou (now at Western Digital), one of Hayward’s graduate students. Employees of California Riverside University and Stanford University also participated in the studies.

Looking ahead, the team aims to improve control over material movement. Currently, a material can change from a flat state to a curved state simply by bending and stretching. Their aim is also to increase efficiency by maximizing the amount of mechanical energy produced compared to the light energy input.

“We still have a long way to go before these materials can truly compete with current actuators, especially in terms of performance,” says Hayward. “But this work is an important step in the right direction and gives us a roadmap for how we can achieve this in the years to come.” Source