Medical micro-robots automatically change shape to swim through the body
It's looking more and more likely that tiny robots could one day be swimming and crawling through your body, delivering drugs or scrubbing out your arteries. But the human body is full of wildly different environments, so any robots exploring them need to be able to adapt on the fly. Now, researchers at EPFL and ETH Zurich have developed micro-robots that can automatically morph in response to their surroundings.
The micro-robots are made of layers of biocompatible hydrogel folded up like origami – a strategy seen in many other tiny robots designed for use in the body. Tiny magnetic particles are embedded into the material, so it can be driven from outside the body using a varying electromagnetic field.
But the new robots are also designed with a touch of autonomy in getting around – they change their shape based on their surroundings, folding and unfolding themselves into the most efficient shape for the job. For example, the team found that a tube-shaped body and a flat tail to paddle was the best design for swimming through a liquid with low viscosity, while a helix shape was better at getting through more viscous fluids. To let the robot make the transition between the two shapes by itself, the team designed it so it was triggered by a higher sucrose concentration.
"Our robots have a special composition and structure that allow them to adapt to the characteristics of the fluid they are moving through," explains Selman Sakar, lead researcher on the study." For instance, if they encounter a change in viscosity or osmotic concentration, they modify their shape to maintain their speed and maneuverability without losing control of the direction of motion."
The researchers tested the robots by running them through narrow glass tubes designed to mimic blood vessels, where they swam in fluids of different viscosities that were flowing at different rates. That helped the team figure out which shapes were better in which environments.
The team has been developing micro-robots for years, but these look like the most advanced ones to date. In future, this work could lead to robots that deliver drugs directly to the parts of the body that need them, or even perform surgery as uninvasively as possible.
The research was published in the journal Science Advances, and the micro-robots can be seen in action in the video below.