Morphing metal to change the future of soft robotics

Robotics is the branch of engineering that deals with the design, construction and application of robots. These technologies deal with automated machines, which can act as a substitute of humans in conditions where safety is at threat. 

Bio-inspired robotics is taking a lead in the field of robotics. This area is about making robots that are inspired by biological systems. It is different from Biomimicry which is copying the nature. Soft robotics is an offshoot of biomimicry. In this article, I am going to discuss the latest trend in soft robotics. 

A team of engineers from Cornell University, led by Professor Rob Shepherd, has created a hybrid material that they say could enable robots or vehicles to change shape to carry out specific tasks.

Imagine an aircraft that could alter its wings’ shape mid-flight and, like a pelican, dive into the water before morphing into a submarine. Professor Shepherd and his team might help make this futuristic vehicle a reality soon. “Sometimes you want a robot, or machine, to be stiff,” said Prof Shepherd, adding, “But when you make them hard, they can’t morph well. This material will enable a soft robot to morph its structure and also be stiff and bear the load.”

The key is a hybrid material consisting of stiff metal and soft porous rubber foam that exhibits the best properties of both – stiffness and elasticity. The material also can self-heal following damage.

“It’s a sort of like us – we have a skeleton, plus soft muscles and skin,” he said. “Unfortunately, that skeleton limits our ability to change shape -unlike an octopus, which does not have a skeleton.”

The idea blends the rigidity and load-bearing capacity of humans with their ability to alter dramatically shape, like an octopus.

“That’s what this idea is about – to have a skeleton when you need it, melt it away when you don’t, and then reform it,” Professor said.

The material is said to combine a soft alloy called Field’s Metal with porous silicone foam. In addition to its low melting point of 62°C, Field’s Metal was chosen because, unlike other alloys, it contains no lead. 

For this material, the elastomer foam is dipped into the molten metal and then placed in a vacuum so that the air in the foam’s pores is removed and replaced by the alloy. The pore is about 2 mm, and that helps it to be tuned to create a stiffer or a more flexible material.

When it is tested to gauge strength and elasticity, the material is said to have shown an ability to deform when heated above 62°C, regain rigidity when cooled, and then return to its original shape and strength when reheated.

The work was supported by the U.S. Air Force Office of Scientific Research, the National Science Foundation, and the Alfred P. Sloan Foundation.

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