Researchers in US develop tiny crab robot that could be used inside human bodies

The tiny crab robot developed at Northwestern University
The smaller the robot, the quicker the team can make it walk. Photo credit: Supplied / Northwestern University

A tiny new robot has been developed that ultimately may be used inside human bodies for healthcare purposes - and it's shaped like a peekytoe crab.

Engineers at Northwestern University in Illinois, US say they have developed the smallest ever, remote-controlled walking robot at just half-a-millimetre wide.

The research, published at the end of last week in the journal Science Robotics, says the crab-bot can also bend, twist, crawl, walk, turn - and even jump.

"Robotics is an exciting field of research, and the development of microscale robots is a fun topic for academic exploration," said John A. Rogers, who led the experimental work.

"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."

Yonggang Huang, who led the theoretical work, said the technology means the crab can walk with an average speed of half its body length per second. 

"This is very challenging to achieve at such small scales for terrestrial robots."

The tiny crab robot developed at Northwestern University
Photo credit: Supplied / Northwestern University

Last year the same team made a winged microchip branded as the smallest-ever human-made flying structure, and have also developed millimetre-sized robots resembling inchworms, crickets and beetles.

The tiny crab is designed to be used in a way that doesn't require complex hardware, hydraulics or electricity and walks thanks to the "elastic resilience" of its body.

The robot is essentially made from an alloy material that has shape-memory. When heated, the ally transforms to its 'remembered' shape.

The tiny crab robot developed at Northwestern University
Photo credit: Supplied / Northwestern University

The Northwestern University researchers created movement by using a scanned laser beam to rapidly heat the robot at targeted locations across its body. A thin coating of glass then helps return it to its other structure when it cools. 

"Not only does the laser remotely control the robot to activate it, the laser scanning direction also determines the robot's walking direction," the researchers wrote.

"Scanning from left to right, for example, causes the robot to move from right to left."

Rogers said because the structures are so tiny, they cool very fast. So much so, that reducing the size of the robot allows them to run faster.

Using an assembly method inspired by a pop-up children's book the team is able to make robots of various shapes and sizes, and it was the students who helped the research who decided on the final form.

"With these assembly techniques and materials concepts, we can build walking robots with almost any size 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."