Each is about half a millimeter wide, which is less than the thickness of a United States penny.
It took a year and a half to create the tiny metal creatures, said co-author John A. Rogers, Louis Simpson and Kimberly Querrey, a professor of materials science and engineering at Northwestern University.
His team consisted of students from different academic backgrounds who combined critical and creative thinking skills to design crab-like robots as well as other animals such as worms and crickets, he said.
Some students found the crab movement sideways fun, which was the inspiration behind the crab robot, Rogers said. The tiny robot can also twist, twist and jump, he added.
Giving life to robots
The robots, which are made of a malleable alloy with shape memory, start as flat objects, similar to a piece of paper. The legs and arms are bent so the robot can stand, he said. The crab stays on its feet until heat is used to make the crab move, Rogers said.
An alloy metal object with shape memory can be deformed but returns to its original shape once heat is applied to it, he explained.
The “original” shape of the crab is when it is flat while the “deformed” position is when the arms and legs are bent.
The crab stays on its feet until the heat from the lasers is used to make the crab move, Rogers said.
His team would warm up some joints to partially restore them to their original flattened state. When the heat was applied again and again in a certain row, the crabs were able to move, similar to how people bend and straighten their legs to walk.
According to Rogers, lasers were used to apply heat to different parts of the crab robot to create motion.
“A laser is a convenient way to do this because we can focus the light on a very tiny point and we can scan that point around to illuminate different parts of the robot’s body in a sequence of time,” he said.
A promising future
The robots are still in development and were created primarily for academic purposes, but the technology used to make the tiny crabs has potential, Rogers said.
Tiny crab robots could be used to perform minimally invasive surgeries or to assist in assembling and repairing small-scale machinery, he said.
Meanwhile, Rogers has challenged his team to expand the robot’s capabilities.
“As an ambitious target, I asked the students to see if they could find a way to fly these robots – perhaps impossible, but fun to think about,” he said.