New approach to soft robotics encourages sustainability

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A new study details a new approach to designing soft robotics and metamaterials by utilising computer algorithms.

Researchers from the University of Illinois Urbana-Champaign and Technical University of Denmark said they can now build multimaterial structures without dependence on human intuition or trial-and-error to produce highly efficient actuators and energy absorbers that mimic designs found in nature.

Led by Illinois civil and environmental engineering Professor Shelly Zhang, the study uses optimisation theory and an algorithm-based design process called topology optimisation. Also known as digital synthesis, the design process builds composite structures that can precisely achieve complex prescribed mechanical responses.

“The complex mechanical responses called for in soft robotics and metamaterials require the use of multiple materials — but building these types of structures can be a challenge,” Zhang said in a statement. “There are so many materials to choose from, and determining the optimal combination of materials to fit a specific function presents an overwhelming amount of data for a researcher to process.”

Zhang’s team focused on designing macroscale structures with the prescribed properties of swift stiffening, large-scale deformation buckling, multiphase stability and long-lasting force plateaus.

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According to the team, the new digital synthesis process generated structures with optimal geometric characteristics composed of the optimal materials for the prescribed functions.

Researchers ended up with model devices made from two different polydimethylsiloxane (PDMS) elastomers with a basic geometry that looked ‘remarkably’ like the legs of a frog, they said — or a family of three frogs, each with different geometries that use the two PDMS elastomers in various arrangements that function very much like biological muscle and bone.

“We have designed reusable and fully recoverable energy dissipators, which is aligned with today's demand for sustainable devices that are good for the environment,” Zhang added. “These are not single-use devices. We designed them using purely elastic materials, allowing us to reuse them many times.”

The team said its digital synthesis technique will increase the range of programmable materials that can handle complex, previously impossible mechanical responses, particularly in the area of soft robotics and biomedical advices.

Research was supported by the US National Science Foundation and the Villum Foundation. The study is published in the Proceedings of the National Academy of Sciences.