These tiny robots inspired by starfish larva move courtesy of ultrasound

Microrobots have been a longtime fascination for many in the industry. Such technologies could ultimately provide a slew of applications, including a handful of useful features in healthcare. Things like targeted delivery of medication and microsurgical procedures are frequently mentioned.

Mobility is among the biggest questions that arise from the tech. Specifically, how can roboticists get them to move without batteries and other technologies on board. Magnets are a fairly common suggestion, but a team at ETH Zurich is exploring an altogether different solution: ultrasound.

The robots, which measure smaller than the diameter of a human hair, were created using photolithography. They’re covered with synthetic versions of the sort of cilia that cover starfish larva. In the biological example, these ultra-fine hair-like structures beat the surrounding water in patterns that create small vortexes, propelling the young echinoderms through the fluid. Effectively, the system either pushes water or pulls it in.


The team says it was able to create similar propulsion in its tiny robots by applying ultrasound waves, allowing them to swim in a straight line. The objects you see around the robot in the photos and video are plastic microbeads added to the water to demonstrate how it moves in circular patterns around the robot.

Drug delivery is the most broadly discussed application here -- specifically, the ability to deliver medication directly to the site of something like a stomach tumor. Doing so could ensure that it’s used more efficiently, while reducing potential side effects.

“But before this vision can be realized, a major challenge remains to be overcome: imaging,” the school writes. “Steering the tiny machines to the right place requires that a sharp image be generated in real time. The researchers have plans to make the microrobots more visible by incorporating contrast agents such as those already used in medical imaging with ultrasound.”