In the final days of 2025, researchers from ETH Zurich demonstrated a new type of soft robot capable of imitating the smooth movements of a stingray thanks to unique artificial muscles made from microscopic air bubbles. This development, known in the scientific community as Stingraybot, illustrates not only progress in soft robotics, but also a fundamental shift in how machines can move and interact with their environment without traditional actuators and batteries. ETH Zürich
Soft robotics—a field inspired by biological organisms—has been developing rapidly for several years, but this particular work opens up entirely new horizons. The robot’s “muscles” are created from thin silicone membranes that trap microscopic air bubbles when immersed in liquid. When exposed to ultrasonic waves, these bubbles begin to vibrate, causing the membranes to contract and bend, producing controlled, fluid movements. This approach eliminates the need for conventional motors, batteries, and wiring, making the design exceptionally lightweight and flexible.
What at first glance may look like a toy or a bionic imitation is in fact a fundamental step toward robots capable of safely and effectively interacting with living tissues and complex environments. Even now, such muscles are being used for soft gripping of delicate objects—such as live fish—without causing damage, while the robot itself demonstrates the ability to maneuver in liquid, reproducing the wave-like motions characteristic of living beings.
Potential applications extend far beyond a “water toy.” Miniature robots based on microbubble muscle technology could be used for drug delivery inside the body, for work in narrow cavities—such as the intestines—or for minimally invasive medicine, where flexibility, adaptability, and safety are critical. In the long term, such machines could replace a range of surgical instruments, operating where rigid mechanisms simply cannot pass.
Source of the research: ETH Zurich — ethz.ch
