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| Scientists in Korea have developed a soft robot that can degrade on demand into an oily liquid. Courtesy of Seoul National University |
By Holly Chik
When a military robot entered an enemy camp to collect intelligence, it was accidentally detected and captured by soldiers there. But after it was brought to a lab for investigation, all that was left was a puzzling puddle of oily liquid.
This scenario is what a team of scientists in Korea said their soft robot that can decompose on demand might do one day.
A robot with the special material could also be deployed to explore dangerous locations like the deep sea or radioactive areas where retrieving the robot would be infeasible or too expensive, they said.
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| The soft gaiting robot with integrated electronic devices can terminate its existence and disassemble. Courtesy of Seoul National University |
The researchers from Seoul National University, Ulsan National Institute of Science and Technology, Korea Institute of Science and Technology and Sogang University published their findings in the peer-reviewed journal Science Advances on Saturday.?
The first author of the study Oh Min-ha, a graduate student of the department of materials science and engineering at SNU, said the team spent more than two years searching for ways to trigger a material to be transient.
"Silicone elastomer is the gold standard material for soft robotics," he said, referring to a rubber-like material that is highly elastic and stretchable. "But it has very high cross-link density, so it is hard to decompose chemically."
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| The silicone composite material is hyper-elastic and tear-resistive, making it suitable for creating soft robots. Courtesy of Seoul National University |
To break the material chemically, the team mixed a substance known as DPI-HFP, which emits fluoride ions under UV light exposure, into commercial silicone resin. Once activated, the generated fluoride ion would attack the bonds in the silicone elastomer and trigger the robot to degrade, according to the study.
When the disintegration system within the robot is triggered by a tactile sensor, UV LEDs installed in the robot would start operating and activate a heater after 30 minutes. The robot would then be heated up to 140 degrees Celsius to speed up the disassembly process, leaving behind an oily liquid residue in 90 minutes.
Co-author Lee Seung-min, also a graduate student researcher at SNU, said while this study focuses on the robot frame, the team has also found that DPI-HFP is capable of breaking bonds in copper, a metal commonly used to make wires and circuit boards, showing the possibility for other electronic parts in the robot to be made transient.
Lee, who researches at the SNU bio-Interfaced electronics laboratory along with Oh, added that the soft material is highly versatile and can be used to design robots in different shapes, sizes and mechanisms for movements in future studies.?
In this study, the small robot with a rectangular body and four supporting feet moves by bending motions induced by an air pump.
"We have mimicked death in a lifecycle where the robot could end itself," she said.?
Holly Chik is a science reporter with the South China Morning Post. She is currently based in Seoul, reporting for both The Korea Times and the South China Morning Post under an exchange program.
