Synthetic materials mimic living creatures
'Robotic soft matter' bends, rotates and crawls when hit with light

Date:
June 22, 2020
Source:
Northwestern University
Summary:
Researchers have developed a family of soft materials that imitates
living creatures. When hit with light, the film-thin materials
come alive -- bending, rotating and even crawling on surfaces.



FULL STORY ========================================================================== Northwestern University researchers have developed a family of soft
materials that imitates living creatures.


==========================================================================
When hit with light, the film-thin materials come alive -- bending,
rotating and even crawling on surfaces.

Called "robotic soft matter by the Northwestern team," the materials
move without complex hardware, hydraulics or electricity. The researchers believe the lifelike materials could carry out many tasks, with potential applications in energy, environmental remediation and advanced medicine.

"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 experimental 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."
The research will be published on June 22 in the journal Nature Materials.

Stupp is the Board of Trustees Professor of Materials Science and
Engineering, Chemistry, Medicine and Biomedical Engineering at
Northwestern and director of the Simpson Querrey Institute He has
appointments in the McCormick School of Engineering, Weinberg College
of Arts and Sciences and Feinberg School of Medicine. George Schatz, the Charles E. and Emma H. Morrison Professor of Chemistry in Weinberg, led computer simulations of the materials' lifelike behaviors. Postdoctoral
fellow Chuang Li and graduate student Aysenur Iscen, from the Stupp and
Schatz laboratories, respectively, are co-first authors of the paper.



========================================================================== Although the moving material seems miraculous, sophisticated science is
at play. Its structure comprises nanoscale peptide assemblies that drain
water molecules out of the material. An expert in materials chemistry,
Stupp linked the peptide arrays to polymer networks designed to be
chemically responsive to blue light.

When light hits the material, the network chemically shifts from
hydrophilic (attracts water) to hydrophobic (resists water). As the
material expels the water through its peptide "pipes," it contracts --
and comes to life. When the light is turned off, water re-enters the
material, which expands as it reverts to a hydrophilic structure.

This is reminiscent of the reversible contraction of muscles, which
inspired Stupp and his team to design the new materials.

"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."
For Northwestern's bio-inspired material, localized light can trigger directional motion. In other words, bending can occur in different
directions, depending on where the light is located. And changing the
direction of the light also can force the object to turn as it crawls
on a surface.

Stupp and his team believe there are endless possible applications
for this new family of materials. With the ability to be designed in
different shapes, the materials could play a role in a variety of tasks, ranging 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,"
he said. "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."

========================================================================== Story Source: Materials provided by Northwestern_University. Original
written by Amanda Morris. Note: Content may be edited for style and
length.


========================================================================== Related Multimedia:
* YouTube_video:_Synthetic_material_walks ========================================================================== Journal Reference:
1. Chuang Li, Aysenur Iscen, Hiroaki Sai, Kohei Sato, Nicholas
A. Sather,
Stacey M. Chin, Zaida A'lvarez, Liam C. Palmer, George C. Schatz,
Samuel I. Stupp. Supramolecular-covalent hybrid polymers for
light-activated mechanical actuation. Nature Materials, 2020; DOI:
10.1038/s41563-020- 0707-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/06/200622132821.htm

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