Physicists build muscle for shape-changing, cell-sized robots

An electricity-conducting, environment-sensing, shape-changing machine the size of a human cell? Is that even possible to build robot? Yes its possible. The physicist have actually built “Muscle” for one.

  • The research team has already made a robot exoskeleton that can rapidly change its shape upon sensing chemical or thermal changes in its environment.
  • And, they claim, these microscale machines equipped with electronic, photonic and chemical payloads and could become a powerful platform for robotics at the size scale of biological microorganisms.
  • They were trying to build for Electronics ”EXOSKELETON”. They can make little computer chips that do a lot of information processing but they were not able move or bend.
  • The machines move using a motor called a bimorph. A bimorph is an assembly of two materials in this case, graphene and glass that bends when driven by a stimulus like heat, a chemical reaction or an applied voltage.
  • The shape change happens because, in the case of heat, two materials with different thermal responses expand by different amounts over the same temperature change.
  • As a consequence, the bimorph bends to relieve some of this strain, allowing one layer to stretch out longer than the other. By adding rigid flat panels that cannot be bent by bimorphs, the researchers localize bending to take place only in specific places, creating folds.
  • With this concept, they are able to make a variety of folding structures ranging from tetrahedra (triangular pyramids) to cubes.
  • In the case of graphene and glass, the bimorphs also fold in response to chemical stimuli by driving large ions into the glass, causing it to expand.
  • Typically this chemical activity only occurs on the very outer edge of glass when submerged in water or some other ionic fluid.
  • Since their bimorph is only a few nanometers thick, the glass is basically all outer edge and very reactive.
  • The bimorph is built using atomic layer deposition chemically “painting” atomically thin layers of silicon dioxide onto aluminum over a cover slip then wet-transferring a single atomic layer of graphene on top of the stack.
  • The result is the thinnest bimorph ever made. One of their machines was described as being “three times larger than a red blood cell and three times smaller than a large neuron” when folded.
  • Folding scaffolds of this size have been built before, but this group’s version has one clear advantage.
  • And due to graphene’s relative strength, it can handle the types of loads necessary for electronics applications.
  • For now, these tiniest of tiny machines have no commercial application in electronics, biological sensing or anything else. But the research pushes the science of nanoscale robots forward.
  • There are no ‘muscles’ for small-scale machines, so they were building the small-scale muscles.


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