August 2, 2022 – Imagine being transported to the operating room where your surgical team is waiting – the surgeon, the anesthetist and… a little robot crab.

Northwestern University scientists have built a super-small crab robot that could one day perform tricky surgical tasks — entering your body to suture small ruptured arteries, clear clogged arteries, or track down cancerous tumors.

The six-legged, half-millimetre-wide peekytoe crab, described in a recent issue of Scientific robotics, is the smallest remote-controlled walking robot in the world. It can bend, twist, walk and jump and is operated using a remote-controlled laser.

It’s one of the latest advances in research spanning a decade that aims to create miniature machines to perform hands-on work in hard-to-reach places. This synthetic crustacean and other “microrobots” may be helping surgical teams sooner than you think, thanks to advances in robotics and materials science. But what must happen before this future becomes a reality?

The making of a robot crab

Making a microchip-sized robot crab is ‘pretty simple’, says bioelectronics engineer John Rogers, PhD, who conducted the research. “It consists of three types of materials: a polymer, a shape memory alloy and glass.

Polymer, a plastic-like material, is used in microelectronics. The second component, the shape memory metal alloy, is bonded to the polymer to form the joints and legs. The third component is a thin layer of glass applied to the entire exterior of the robot’s body.

“Glass provides an exoskeleton. This gives rigidity to the entire robot body,” says Rogers.

The robot operator points a laser at a specific location on the crab, triggering a thermal mechanism that makes the robot move.

“By shining it on certain limbs, we can create a specific gait,” says Rogers, explaining that the heat “unfolds” the crab. When the robot cools, it returns to its original shape. This folding and unfolding creates locomotion – the crab walks.

Rogers credits his students for choosing the crab – they liked the way it moved sideways – but he says any creature could probably be made smaller.

How will we use tiny robots in medicine?

While Rogers is reluctant to sell any specific medical use too hard, surgical applications seem the most promising for this technology. For use deep inside the human body, Rogers says, “you would probably want a swimmer – like a fish. There are other groups working on swimmers.

Renee Zhao, PhD, assistant professor of mechanical engineering at Stanford University, is one such scientist. in a newNature Communicationarticle, she and her colleagues report on their “spinning wireless amphibious origami millirobot.” (Say that five times quickly.)

The mini robot – closer to the size of a finger – looks like a small cylinder and features an origami-inspired design that twists and curls. It glides through viscous liquid and over smooth surfaces and masses (such as human organs), rolling, tilting, and rotating using a remote magnet. The folding and unfolding of the cylinder serves as a pumping mechanism and can be used for targeted delivery of liquid medication. It could, for example, carry drugs around the body to help stop internal bleeding, Zhao says.

“We are improving the system by further reducing it for biomedical applications in tighter environments like blood vessels,” she says.

In their paper, Zhao and his co-authors also note that mini-cameras and mini-tweezers could be placed inside the millirobots to perform endoscopy and biopsy procedures, which, in theory, could carry less risk. for patients than current techniques.

But there was a lot of trial and error during the design phase of the robot, Zhao says.

“The tricky part is to have an optimized swimming performance,” she says, because the density of the robot must be very close to the density of the liquid in which it “swims”.

And after

At present, Zhao’s amphibious robot is still in the testing stages before animal testing. If it clears those hurdles, it will then be studied in human clinical trials.

That means it’s likely to be years before swimming cylinders — or robot crabs, for that matter — help heart surgery teams or suture organs.

“This is early-stage exploratory work,” says Rogers. “We are trying to introduce ideas as part of a larger community of researchers who are pursuing micro-robotic technologies, with the hope that over time these technologies will eventually lead to practical clinical uses for purposes. surgical. It really is a starting point.