Research published yesterday in the journal Nature Materials describes the development of “robotic soft matter,” a class of soft materials that imitates living creatures. The technology comes from scientists at Northwestern University who hope that the materials could be used in advanced medicine and environmental remediation.
"We live in an era in which increasingly smarter devices are constantly being developed to help us manage our everyday lives," said lead researcher Samuel I. Stupp from Northwestern. "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."
By “capabilities of living creatures,” Stupp is referring to the materials’ ability to bend, rotate, and move on surfaces when interacting with light. They do so without complex hardware, hydraulics, or electricity.
How? The structures are made to mimic contracting muscles. They consist of nanoscale peptide assemblies linked to polymer networks designed that are chemically responsive to blue light. So, when the material interacts with blue light, it goes from hydrophilic to hydrophobic and drains water molecules out of the material, thus contracting (and moving!). When light is subsequently taken away, the opposite process occurs, making the material expand. In this way, the material can be controlled by directing the light in certain manners.
"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 said. "Muscles do this using a chemical fuel rather than light to generate mechanical energy."
What applications could these materials have? The options are limitless, say the researchers, from environmental clean-up to brain surgery.
"These materials could augment the function of soft robots needed to pick up fragile objects and then release them in a precise location," said 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 seawater or even undertake healing tasks to repair defects in batteries, membranes and chemical reactors."