Researchers from the University of Colorado, Boulder, have developed a groundbreaking material that has the ability to convert light into a substantial mechanical force, allowing it to lift objects that are 1,000 times its own mass. This photomechanical material, made from tiny organic crystals, has the potential to drive wireless, remote-controlled systems that power robots and vehicles, without the need for heat or electricity.
Photomechanical materials are designed to convert light directly into mechanical force, which is achieved through a complex interplay between photochemistry, polymer chemistry, physics, mechanics, optics, and engineering. The use of photomechanical actuators, which are responsible for physical movements, has gained popularity due to the ability to control them externally by manipulating light conditions.
While photomechanical materials have shown promise, there have been challenges in harnessing molecular-level motions to generate a large-scale mechanical response. Previously, reactive molecules needed to be organized to push in the same direction, often requiring the use of an ordered host material or ordered self-assembly of molecules. To overcome these challenges, the researchers from the University of Colorado, Boulder, developed an innovative approach.
The researchers used an array of tiny organic crystals derived from diarylethene, which act as the photoactive component. These crystals were then set within a polymer material with micron-sized pores. By growing the crystals within the pores, their durability and energy production when exposed to light were significantly enhanced. This approach also prevented the crystals from fracturing upon light exposure. The composite material demonstrated flexibility and durability, able to be bent to 180° without breaking or sacrificing its photomechanical response. It also exhibited reversible bending and unbending when alternating between UV and visible light.
To test the lifting power of the photomechanical crystals, weight-lifting experiments were conducted. The crystals were able to act as actuators, moving a load when they changed shape with a load attached. The impressive result showed that a 0.02-mg crystal array was able to lift a 20-mg nylon ball, which is 1,000 times its own mass.
According to Ryan Hayward, the corresponding author of the study, “What’s exciting is that these new actuators are much better than the ones we had before. They respond quickly, last a long time and can lift heavy things.”
The researchers believe that this innovative material has the potential to be used in various applications, such as replacing electrically wired actuators in robots and vehicles or powering drones through laser beams instead of traditional bulky batteries. However, further improvements are needed to enhance its control and efficiency. The material’s movement currently transitions from a flat to a curved state by bending and unbending, and efforts are being made to achieve greater control over its movement. Additionally, the researchers aim to increase efficiency, maximizing the amount of mechanical energy produced compared to light energy input.
Hayward acknowledges that there is still progress to be made before these materials can compete with existing actuators in terms of efficiency. Nevertheless, this study is an important step in the right direction and provides a roadmap for future advancements in the coming years.
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1. Source: Coherent Market Insights, Public sources, Desk research
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