A team of engineers at the Northwestern University in Illinois devised a minute remote-controlled robotic crab. With a width of just half a millimeter, it is the smallest walking remote-controlled robot ever created.
As of yet, we are still dealing with exploratory research, but the team has hopes for their technology to become a stepping stone toward practically deployable mini robots capable of performing challenging tasks in cramped spaces which are unreachable with contemporary technology.
Tiny crab robot placed on the edge of a coin - (Image Credit: Northwestern University)
Worthwhile use cases
Because these mini robots are capable of bending, twisting, turning, walking, and jumping while being controlled remotely, they could potentially be useful as agents to assemble or restore tiny machines or structures.
They could conceivably also be deployed as 'surgical assistants' to stem internal bleeding, remove cancerous tumors, or alleviate clogged arteries in minimally invasive procedures.
Dr. Yonggang Huang, who led the underlying theoretical work of the project, explained that their technology allows for a selection of different movements while averaging a speed of half its body length per second. Huang: "This is very challenging to achieve at such small scales for terrestrial robots."
Innovative engineering
The robotic crab, which is smaller than the size of a flea, is not propelled by complicated machinery, hydraulics, or electricity. Instead, its ability comes from the elastic strength of its body.
The team employed a shape-memory alloy material to build the robot, which, when heated, returns to its "memorized" shape. In this instance, the researchers utilized a scanning laser beam to quickly heat the robot at several specific spots across its body. When cooled, a thin layer of glass restores the distorted component of the structure to its original shape.
A closer look at the tiny robotic crab - Image Credit: Northwestern University
The tiny crab as it transitions from one phase to the next, from distorted to memorized shape and back. The laser not only activates the robotic crab remotely, but its scanning direction also determines the robot's walking path. For example, scanning from right to left leads the crab to move from left to right as well.
Dr. John Rogers, who led the experimental work of the project, explains that the cooling happens very quickly due to the microscopic size of these robots. As a matter of fact, he noted that making them smaller, perhaps counterintuitively, allows them to actually move faster.
Manufacturing minuscule robots
Huang and Rodges used a method they presented eight years ago to manufacture these tiny critters — a pop-up assembly method inspired by a child's pop-up book.
To begin, the team created flat, planar geometries for the walking crab constructs. These precursors were then attached to a somewhat stretched rubber substrate. A controlled buckling process happens when the stretched substrate is relaxed, causing the crab to "pop up" into precisely specified three-dimensional shapes.
Above mentioned method of manufacturing allowed the team to create miniature robots of numerous different sizes and shapes. So why specifically these cute miniature crabs?
We can thank a 'creative whim' from the collaborating students for that. According to Rogers, the students felt inspired and amused by the sideways crawling motions of tiny crabs.
The team has published their research in the peer-reviewed science journal Science Robotics, listed below for those interested in more details and background information.
Sources and further reading on the subject:
Submillimeter-scale multimaterial terrestrial robots - (Science Robotics)
Northwestern University
Unusual mini-robot capable of transporting small packages without the need for chips or batteries - (Universal-Sci)
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