Physicists at Bath University have found a way to coat soft robots with materials that allow them to move and function more purposefully.
The research, conducted in collaboration with Birmingham University, is described in: scientific progress†
With further development, it may be possible to determine the shape, movement and behavior of a soft solid by human-controlled activity on its surface rather than by its natural elasticity.
According to the team, the surface of an ordinary soft material always shrinks into a sphere, but active matter can be designed to counteract this tendency. An example is a rubber ball wrapped in a layer of nano-robots, where the robots are programmed to work together to deform the ball into a new, predetermined shape.
It is hoped that active matter will lead to a new generation of machines whose function comes from the bottom up; instead of being controlled by a central controller, these new machines would be made of individual active units that work together to determine the machine’s movement and function.
MORE OF MATERIALS
This concept allowed scientists to design soft machines with arms made of flexible materials that are powered by robots embedded in their surface. They can also adjust the size and shape of drug delivery capsules. Coating the surface of nanoparticles in a responsive, active material could have a positive effect on a drug’s interaction with cells in the body.
According to Bath University, work on active matter challenges the assumption that the energetic cost of the surface of a liquid or soft solid must always be positive, because a certain amount of energy is always required to create a surface.
In a statement, Dr. Jack Binysh, lead author of the study: “Active matter allows us to look in a new light at the well-known rules of nature – rules such as the fact that surface tension must be positive. See what happens when we break these rules and how we Being able to take advantage of the results is an exciting place to do research.”
Corresponding author Dr. Anton Souslov added: “This study is an important proof of concept and has many useful implications. For example, future technology could produce soft robots that are much softer and better at picking up and manipulating delicate materials.”
For the study, the researchers developed theory and simulations describing a 3D soft solid whose surface experiences active stresses. They found that these active stresses expand the surface of the material, pulling the solid beneath it and causing a global change in shape. The researchers found that the precise shape assumed by the solid could then be modified by changing the material’s elastic properties.
In the next phase of this work, the researchers will apply this general principle to design specific robots, such as soft arms or self-swimming materials. They will also look at collective behavior and observe what happens when many active solids are packed together.
This work was funded by the Engineering and Physical Sciences Research Council through a New Investigator Award†