ROBOTICS
Virginia Tech physicists propose path to faster, more flexible robots
Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery
IMAGE:
VIRGINIA TECH PHYSICIST C. NADIR KAPLAN (AT LEFT) AND DOCTORAL CANDIDATE CHINMAY KATKE (RIGHT) DISCOVERED A MICROSCOPIC PHENOMENON THAT COULD GREATLY IMPROVE THE PERFORMANCE OF SOFT DEVICES, SUCH AS AGILE FLEXIBLE ROBOTS OR MICROSCOPIC CAPSULES FOR DRUG DELIVERY. PHOTO BY SPENCER COPPAGE FOR VIRGINIA TECH.
view moreCREDIT: PHOTO BY SPENCER COPPAGE FOR VIRGINIA TECH.
In a May 15 paper released in the journal Physical Review Letters, Virginia Tech physicists revealed a microscopic phenomenon that could greatly improve the performance of soft devices, such as agile flexible robots or microscopic capsules for drug delivery.
The paper, written by doctoral candidate Chinmay Katke, assistant professor C. Nadir Kaplan, and co-author Peter A. Korevaar from Radboud University in the Netherlands, proposes a new physical mechanism that could speed up the expansion and contraction of hydrogels. For one thing, this opens up the possibility for hydrogels to replace rubber-based materials used to make flexible robots—enabling these fabricated materials to perhaps move with a speed and dexterity close to that of human hands.
Soft robots are already being used in manufacturing, where a hand-like device is programmed to grab an item from a conveyer belt—picture a hot dog or piece of soap—and place it in a container to be packaged. But the ones in use now lean on hydraulics or pneumatics to change the shape of the “hand” to pick up the item.
Akin to our own body, hydrogels mostly contain water and are everywhere around us, e.g., food jelly and shaving gel. Katke, Korevaar, and Kaplan’s research appears to have found a method that allows hydrogels to swell and contract much more quickly, which would improve their flexibility and capability to function in different settings.
What did the Virginia Tech scientists do?
Living organisms use osmosis for such activities as bursting seed dispersing fruits in plants or absorbing water in the intestine. Normally, we think of osmosis as a flow of water moving through a membrane, with bigger molecules like polymers unable to move through. Such membranes are called semi-permeable membranes and were thought to be necessary to trigger osmosis.
Previously, Korevaar and Kaplan had done experiments by using a thin layer of hydrogel film comprised of polyacrylic acid. They had observed that even though the hydrogel film allows both water and ions to pass through and is not selective, the hydrogel rapidly swells due to osmosis when ions are released inside the hydrogel and shrinks back again.
Katke, Korevaar, and Kaplan developed a new theory to explain the above observation. This theory tells that microscopic interactions between ions and polyacrylic acid can make hydrogel swell when the released ions inside the hydrogel are unevenly spread out. They called this “diffusio-phoretic swelling of the hydrogels.” Furthermore, this newly discovered mechanism allows hydrogels to swell much faster than what has been previously possible.
Why is that change important?
Kaplan explained: Soft agile robots are currently made with rubber, which “does the job but their shapes are changed hydraulically or pneumatically. This is not desired because it is difficult to imprint a network of tubes into these robots to deliver air or fluid into them.”
Imagine, Kaplan said, how many different things you can do with your hand and how fast you can do them owing to your neural network and the motion of ions under your skin. Because the rubber and hydraulics are not as versatile as your biological tissues, which is a hydrogel, state-of-the-art soft robots can only do a limited number of movements.”
How could this improve our lives?
Katke explained that the process they have researched allows the hydrogels to change shape then change back to their original form “significantly faster this way” in soft robots that are larger than ever before.
At present, only microscopic-sized hydrogel robots can respond to a chemical signal quickly enough to be useful and larger ones require hours to change shape, Katke said. By using the new diffusio-phoresis method, soft robots as large as a centimeter may be able to transform in just a few seconds, which is subject to further studies.
Larger agile soft robots that could respond quickly could improve assistive devices in healthcare, “pick-and-place” functions in manufacturing, search and rescue operations, cosmetics used for skincare, and contact lenses.
JOURNAL
Physical Review Letters
ARTICLE TITLE
Diffusiophoretic Fast Swelling of Chemically Responsive Hydrogels
ARTICLE PUBLICATION DATE
15-May-2024
Scientists made a soft robot that mimics a spider's leg
ESTONIAN RESEARCH COUNCIL
VIDEO:
A SPIDERS LEGS INSPIRED MM-SCALE SOFT EXOSCELETON ENABLED BY LIQUID VIA HYDRATION AND CHARGE TRANSPORT.
view moreCREDIT: TARTU UNIVERSITY ITALIAN INSTITUTE OF TECHNOLOGY
Scientists made a soft robot that mimics a spider's leg
Researchers Indrek Must and Kadri-Ann Valdur of the Institute of Technology of the University of Tartu have created a robot leg modelled after the leg of a cucumber spider. A soft robot created in cooperation with the Italian Institute of Technology could in the future move where humans cannot.
In organisms, fluid is what binds the organs, the blood vessels and the musculoskeletal system as a whole. For example, hemolymph, a blood-like fluid in a spider's body, enables muscle activation and exoskeleton flexibility. It was the cucumber spider inhabiting Estonia that inspired scientists to create a complex soft robot, where soft and rigid parts are made to work together and are connected by a liquid.
According to Indrek Must, Associate Professor of Soft Robotics, the designed soft robot is based on real reason. "Broadly speaking, our goal is to build systems from both natural and artificial materials that are as effective as in wildlife. The robotic leg could touch delicate objects and move in the same complex environments as a living spider," he explains.
In a new research paper published in the journal Advanced Functional Materials, the researchers show how a robotic foot touches a primrose stamen, spider web, and pollen grain. This demonstrates the soft robot's ability to interact with very small and delicate structures without damaging them.
The manufactured leg is the size of a little fingernail and consists of a light-curing resin exoskeleton and an artificial muscle made of polypyrrole. Similar to a natural muscle, a soft robot is activated by an electrical signal. The entire exoskeleton contains an electrolyte solution that surrounds both a stiffer tendon made of resin and an electroactive polymer artificial muscle. The solution behaves like the hemolymph in spiders and affects the properties of the exoskeleton as well as the movement – the liquid makes the exoskeleton more flexible and the leg starts to move due to the change in the shape of the polymer.
Soft robotics is inspired by wildlife. In the future, robots will be able to operate in places where humans cannot or cannot go, for example moving inside a person as a nanorobot during surgery or searching for survivors in a disaster area.
A spiders legs inspired mm-scale soft exosceleton touching plants anthers
CREDIT
Tartu University Italian Institute of technology
JOURNAL
Advanced Functional Materials
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
A Spider Leg-Inspired mm-Scale Soft Exoskeleton Enabled by Liquid via Hydration and Charge Transport
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