World’s smallest “robot” could assist a cardiac surgeon - in some years

A 0.5-mm-long crab made of an elastic silicone-based material can walk, turn, and jump.

It was created by engineers from Northwestern University, and it is the smallest remote-controlled robot in the world so far.

The researchers hope that it will be a step towards mini-robots that will be able to solve practical tasks in narrow spaces, for example in medicine, where one could imagine them used as surgical assistants during operations.

The invention is so far most hindered by the fact that it is not capable of much other than moving across a surface.

According to Peter Bøggild, professor of nanomaterials at DTU, the microrobotics research behind the invention is important, but has a long way to go:

“It’s a fine experiment, and the research in that field is important, but it’s not exactly the kind of thing that makes you think ‘robots are coming’ when you see it.”

Coordinated heating and cooling used for movement

The robot is not directly controlled through electricity, hydraulics, or complex hardware, because it uses the elasticity of the material it is made of. It is a type of so-called shape-memory material, which can transform into a specific shape when heated.

By coordinating this transformation in its legs, the robot can be instructed to move, which is done with the help of a laser device. The laser device directs a beam at the legs to heat them following a specific pattern depending on what position they are in.

“Similar laser tracking is used to measure eye movements during certain operations in hospitals, so it should be able to easily keep track of a such a little guy,” Peter Bøggild explains.

The robot can move at a speed of half its body length (around 0.25 mm) per second and is equipped with two claw-like arms in front, but it is not clear what their use is.

As it is remotely controlled, for example, it does not have a built-in control system or an energy source. It is instead based on a simple design, with a focus on laser coordination of leg movements.

“If we created a scale of 0–10 for what we would ideally like such a small robot to be able to do, this one would probably not be high on the list. With a laser pointer and the right material, many would probably be able to make a slightly larger version themselves,” Peter Bøggild says.

“Miniaturization of robots is incredibly difficult”

He believes that ideally, a robot should be able to do something more. For example, to have more characteristics of a living being with its own control system and energy source.

“A good ideal is to try to copy insects. They are incredibly strong, good at surviving, and turning one material into another,” Peter Bøggild says.

The researchers behind the crab themselves express hopes that their study can contribute to the development of small robots that, for example, could help in the field of medicine and be used in human bodies.

But when building such robots, there are generally three challenges related to their movement. Ideally, they should be able to walk, swim, and fly.

“Of the three, a walking robot is probably the easiest to design, but we haven’t come far even in that field. It's a challenge to make a walking robot that can survive for just a tiny fraction of the time that an insect can,” Peter Bøggild says.

He emphasizes that the research behind the robot is important for the development of the field, but that there is not necessarily any reason to call it a robot. There is also no reason for it to be a crab with claws.

“But robots fascinate us, and it may very well be that we tend to want to create robots, even though we could handle many tasks in different ways. But we will probably not see a robot close to what evolution has created in our lifetime,” Peter Bøggild says.