This sideways-scooting robot crab is so tiny it fits through the eye of a needle

This sideways-scooting robot crab is so tiny it fits through the eye of a needle

The tiny robot crab is small enough to crawl sideways through the eye of a needle. (Image credit: Northwestern University)

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Engineers have developed the world’s tiniest remote-controlled walking robot, and it mimics a mini crab that can shuffle sideways without any wires, hydraulics, electricity or other standard mechanical components.

The robotic crabs — which span just one-fiftieth of an inch wide (0.5 millimeters) wide — can also bend, twist, turn around and even jump. Normally, walking robots have a mechanical design with lots of moving parts powered by a source of electricity. However, these eight-legged critters have a much more simplified design consisting of only a few nifty materials that can be manipulated by lasers.

The crustacean-like robots are made from an elastic “memory-foam” alloy that gets transformed into its 3D shape like a children’s pop-up book: A 2D crab-shaped alloy outline is attached to a stretched-out rubber substrate at the robot’s feet; when the substrate is relaxed and decreases in surface area the material is forced upward into the desired 3D crab shape.

A simulation of the pop-up process that gives the robot its 3D shape. (Image credit: Northwestern University)

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When the 3D alloy is heated by a laser, it tries to revert to its original flattened-out 2D shape. However, before the alloy can fully flatten out, it quickly cools down and springs back into the 3D crab shape. This rapid changing of shape is what gives the robot movement.

A special glass coating on the alloy makes it easier to direct lasers to heat up certain areas of the robot, which allows for a wide range of movements. To make the crab walk sideways, the laser is shone from one side of the body to the other creating a sort of wave through the body as it flattens and springs back into shape; that wave of motion causes the itty-bitty crab to move in the direction of the laser.

A video of the robot flattening and contracting as it is heated and cooled using lasers, allowing it to walk sideways. (Image credit: Northwestern University)

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