Researchers develop tiny robotic crab that is smaller than a flea

30 May 2022

Northwestern University engineers say they have created the world's smallest remote-controlled walking robot. Image: Northwestern University

The engineers believe similar robots could be used in the future to assemble small structures, clear clogged arteries or eliminate tumours inside the human body.

Engineers in the US have created a remote-controlled robot that is so small it can walk on the top of a US penny.

In research published in the journal Science Robotics, a team at Northwestern University said the crab-like robot is 0.5mm wide. Researchers described it as the smallest-ever remote-controlled walking robot, with a size smaller than a flea.

The tiny robot can bend, twist, crawl, walk, turn and even jump, without the use of complex hardware or hydraulics.

The engineers said this is because the robot is powered by the elastic resilience of its body. To construct the robot, the researchers used a shape-memory alloy material that transforms to its remembered shape when heated.

Using a laser, the team is able to heat the robot at specific parts of its body, causing it to change shape. As the robot deforms and goes back to its original shape, it creates locomotion.

“Because these structures are so tiny, the rate of cooling is very fast,” project lead Prof John A Rogers said. “In fact, reducing the sizes of these robots allows them to run faster.”

While the research is in the exploratory phase, the team believes the technology could lead to micro-sized robots that can perform practical tasks in tightly confined spaces.

“You might imagine micro-robots as agents to repair or assemble small structures or machines in industry or as surgical assistants to clear clogged arteries, to stop internal bleeding or to eliminate cancerous tumours – all in minimally invasive procedures,” Rogers said.

Pop-up crab

Rogers and Prof Yonggang Huang, who led the theoretical work, created the robot based on a pop-up assembly method inspired by children’s pop-up books.

The team fabricated precursors to the walking crab structures in flat, planar geometries. They then bonded the precursors onto a stretched rubber substrate.

When the stretched substrate is relaxed, a buckling process occurs that causes the crab to ‘pop up’ into precisely defined three-dimensional forms.

“With these assembly techniques and materials concepts, we can build walking robots with almost any sizes or 3D shapes,” Rogers said. “But the students felt inspired and amused by the sideways crawling motions of tiny crabs. It was a creative whim.”

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Leigh Mc Gowran is a journalist with Silicon Republic