Researchers from Northwestern University have created a family of soft synthetic materials that shift and move just like living creatures.
Called "robotic soft matter" by the team at Northwestern, the materials bend, rotate, and crawl on surfaces once light hits them. They move without any hardware or software telling them to, not even sophisticated hydraulics do the job.
The team believes their creation could be useful in certain applications in energy, environmental remediation, and in advanced medicine.
Their study was published in Nature Materials on Monday.
Living creatures as models
"We live in an era in which increasingly smarter devices are constantly being developed to help us manage our everyday lives," said Northwestern’s Samuel I. Stupp, who led the studies.
"The next frontier is in the development of new science that will bring inert materials to life for our benefit — by designing them to acquire capabilities of living creatures."
It may well look like the moving materials is a natural process, but it took some seriously advanced science to get them to shift in such a way. They are made up of nanoscale peptide assemblies that move all water out of the material. These peptide arrays were linked to polymer networks by Stupp, which were then designed to react to blue light.
As soon as the light hits the structure, the network shifts from absorbing water (hydrophilic) to draining it (hydrophobic). As the materials push the water out of their structure, it contracts and moves. And when the light is switched off, the water is absorbed back into the material, which makes it expand and revert to its original state.
These movements are very similar to how our human muscles work, which is what inspired Stupp and his team in the first place.
"From biological systems, we learned that the magic of muscles is based on the connection between assemblies of small proteins and giant protein polymers that expand and contract," Stupp explained. "Muscles do this using a chemical fuel rather than light to generate mechanical energy."
The reason the materials are able to rotate and shift in different ways depends on where the light hits them. Changing the direction of the light whilst it's already focusing on the material will then make them rotate or crawl in certain ways.
The materials can be made in almost any shape, making them potentially extremely useful for a number of tasks, from brain surgery to environmental clean-ups.
"These materials could augment the function of soft robots needed to pick up fragile objects and then release them in a precise location," as per Stupp.
"In medicine, for example, soft materials with ‘living’ characteristics could bend or change shape to retrieve blood clots in the brain after a stroke. They also could swim to clean water supplies and sea water or even undertake healing tasks to repair defects in batteries, membranes, and chemical reactors."