Remote-controlled robot crab – the smallest in the world

We are used to thinking of robots as machines of "human" dimensions, also thanks to recent developments by companies such as Boston Dynamics . At the same time, however, many institutions and research centers are making progress in the realization of tiny devices, of the order of millimeters. Northwestern University created a remote-controlled crab-shaped robot breaking the record for the smallest size ever.

It can jump, run, walk, crawl, bend and turn, all in just half a millimeter wide, less than a flea. Experimental as it is, the researchers believe this technology can help build micro-robots to perform tasks in confined spaces. Like the human body.

remote controlled robot crab
the little remote-controlled robot crab on the tip of a ballpoint pen. credit: Northwestern University

Features of the remote controlled robot crab

Engineers are no stranger to developing small devices . Published in the journal Science Robotics, their work was led by two academics John A. Rogers and Yonggang Huang. In addition to peekytoe (the crab species from which inspiration), they have also produced tiny models resembling crickets, beetles and worms. The tiny robot is not powered by complex hardware, plumbing or electrical. Its power instead lies in the elastic resilience of its body.

In fact, the researchers used a shape memory alloy material: this contracts into the "remembered" position when heated. The movement takes place thanks to a laser beam that acts on certain parts of the robot. It then returns elastically to its original shape thanks to a thin glass coating. The alternation of these two phases, i.e. contraction and return to the remembered form, favors the locomotion of the peekyote.

remote controlled robot crab
Close up remote controlled robot crab. credit: Northwestern University

As Rogers says, its small size guarantees its rapid movement. Thanks to these, the cooling rate of the part of the structure hit by the laser is very fast. The creature is able to move at the average speed of half its body length per second, precisely at 0.0009km / h . To give a reference, about a quarter of a millimeter per second. Ground-based robots hardly reach such a record on such small scales.

The laser not only allows the remote controlled movement of the robot crab, but also decides its direction. For example, if you point the laser beam from left to right, it will move in the opposite direction.

Side walk. credit: Northwestern University

Manufacturing process

The production of these small objects partly reflects the characteristic of elastic resilience that they themselves possess. Illinois academics made use of a technology they developed eight years ago inspired by pop-up children's books.

First , the team fabricated precursors to the remote-controlled robot crab structures in flat and planar geometries. Then they glued these precursors onto a slightly elongated rubber substrate. When the stretched substrate is relaxed, a controlled deformation process occurs which causes the crab to “pop” into precisely defined three-dimensional shapes.

Pop-up assembly simulation of a single crab robot. credit: Northwestern University

In doing so, the researchers could develop robots of almost any 3D size and shape. The reason for the peekytoe choice, however, was a creative whim of the students, fascinated by the lateral movements of the crab.

Possible applications of the remote controlled robotic crab

Regarding the future use of these devices, the researchers stated:

"One could 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 tumors – all minimally invasive procedures."

John A. Rogers

The potential repercussions are therefore many, especially in those activities where the human being cannot physically reach. Although in its early stages, developing micro-scale robots isn't just a fun topic to explore academically.

The article Remote-controlled robot crab: it's the smallest in the world was written on: Tech CuE | Close-up Engineering .