Northwestern University engineers have developed the world’s smallest remote-controlled robot in the shape of a crab.
The recently developed remote-controlled robot – that is the smallest in the world – stands at half a millimetre wide and is extremely mobile. These minuscule crab-shaped robots that are smaller than a flea, can bend, twist, crawl, walk, turn and even jump.
The research is published in the journal Science Robotics.
Microscale robotics achievement
“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 microrobots 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.”
“Our technology enables a variety of controlled motion modalities and can walk with an average speed of half its body length per second,” added Yonggang Huang, who led the theoretical work. “This is very challenging to achieve at such small scales for terrestrial robots.”
A pioneer in bioelectronics, Rogers is the Louis Simpson and Kimberly Querrey Professor of Materials Science and Engineering, Biomedical Engineering and Neurological Surgery at Northwestern’s McCormick School of Engineering. Huang is the Jan and Marcia Achenbach Professor of Mechanical Engineering and Civil and Environmental Engineering at McCormick and a key member of QSIB.
What powers the world’s smallest remote-controlled robot?
The crab-shaped robot is not powered by complex hardware, hydraulics, or electricity. Instead, its power lies within 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 heat is applied. In this case, the researchers used a scanned laser beam to rapidly heat the robot at different targeted locations across its body. A thin coating of glass elastically returns that corresponding part of its structure to its deformed shape upon cooling.
As the robot changes from one phase to another – deformed to remembered shape and back again – it creates movement. Not only does the laser remotely control the robot to activate it, but it also determines the robot’s walking direction. For instance, scanning from left to right causes the robot to move from right to left.
“Because these structures are so tiny, the rate of cooling is very fast,” Rogers explained. “In fact, reducing the sizes of these robots allows them to run faster.”
To see the robot in action- please see the video below created by Northwestern University, and posted to their YouTube channel – @NorthwesternU.
Building a microrobot
To manufacture such a tiny critter, Rogers and Huang turned to a technique they introduced eight years ago – a pop-up assembly method inspired by a child’s pop-up book.
First, the team fabricated precursors to the walking crab structures in flat, planar geometries. Then, they bonded these precursors onto a slightly stretched rubber substrate. When the stretched substrate is relaxed, a controlled buckling process occurs that causes the crab to ‘pop up’ into precisely defined three-dimensional forms.
The future of this microrobotic technology
With this manufacturing method, the Northwestern team could develop robots of various shapes and sizes.
“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.”
Last September, the same team of engineers introduced a winged microchip that was the smallest-ever human-made flying structure. The researchers also developed millimetre-sized robots resembling inchworms, crickets and beetles. Although the research is currently exploratory, the researchers believe that their technology has the potential to bring the field closer to realising micro-sized robots that can perform practical tasks inside tightly confined spaces.