By Jason Matthews
Unexpected discovery may be useful in various future applications that will no longer need batteries or motors to fuel movement.
Some of the greatest discoveries and inventions in history happened due to luck. We only have Velcro, Post-it notes, and vulcanized rubber due to serendipitous events, and it seems to have happened again with a new discovery that is helping researchers develop self-propelled materials.
There may be some future applications that will no longer require battery technology for propulsion thanks to this discovery - Image Credit: Illus_man via Shutterstock / HDR tune by Universal-Sci
Snap instabilities
Robots are great for many jobs, but they require power and motors to allow them to move. In some situations, this can be a problem such as when making very-small robots or when electrical power supplies are inconvenient or undesirable. A small group of researchers under the supervision of professor Al Crosby, a specialist in polymer science and engineering at the University of Massachusetts Amherst, made the discovery while carrying out a routine experiment watching a gel strip dry. As the strip dried, they observed movement. Most of the movements were slow but there were also very rapid movements that occurred periodically.
After studying the phenomenon, they found that these rapid movements, which they call ‘snap instabilities’, could be controlled and even made to reset themselves repeatedly by carefully adjusting the shape of the strip.
Crosby explained in a press release that several animals and plants, particularly small ones, utilize special parts that function like springs and latches to help them move very quickly, much faster than animals that only use muscles to propel themselves. Plants like the Venus flytrap are great examples of this kind of movement, as are grasshoppers and trap-jaw ants in the animal world. Snap instabilities are one way that nature combines a spring and a latch and are increasingly applied to create fast movements in small robots and other devices, as well as toys like rubber poppers. Nevertheless, Crosby added that most of these snapping devices need a motor or a human hand to continue moving. This discovery might be usable in various applications that will no longer need batteries or motors to fuel movement.
High-speed photographs of an independently hopping polymer shell - Image Credit: UMass Amherst via EurekAlert/AAAS
Developing the technology further
After working out the physics behind the movement, the researchers were able to produce shapes that could move at specific speeds and in predictable ways. These gel shapes were able to reset themselves without any external input, allowing them to carry out the movements repeatedly with nothing but the energy supplied by the surrounding environment.
Crosby continues, "These lessons demonstrate how materials can generate powerful movement by harnessing interactions with their environment, such as through evaporation, and they are important for designing new robots, especially at small sizes where it's difficult to have motors, batteries, or other energy sources."
Cosby and his team have secured funding to develop this technology further from the US Army’s research and development branch.
Ralph Anthenien, branch chief, Army Research Office commented, "This work is part of a larger multidisciplinary effort that seeks to understand biological and engineered impulsive systems that will lay the foundations for scalable methods for generating forces for mechanical action and energy-storing structures and materials. The work will have myriad possible future applications in actuation and motive systems for the Army and DoD."
If you are interested in this subject and would like to learn more about the work mentioned in this article be sure to check out the paper published in Nature Materials, listed below.
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