Bubbling Under

Muscles bend and flex to pull us around, triggered by impulses sent through our nervous system. Here, biotechnologists try a new approach, creating artificial muscles that allow this tiny 'Stingray bot' to swim around a tank of water. Its muscles are strips of flexible membrane each with thousands of tiny cavities covering the robot’s underside from head to tail. Submerged in water, the cavities trap ‘microbubbles’ that respond to different frequencies of ultrasound, generating tiny thrusting forces. By changing the size of the cavities and the frequency of the ultrasound, the researchers pilot the stingray through water – and might one day do the same in human blood vessels or intestines. The researchers also plan to develop similar artificial muscles as wearable technology.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Video from work by Zhan Shi & Zhiyuan Zhang, and colleagues
• Acoustic Robotics Systems Laboratory, Institute of Robotics and Intelligent Systems, Department of Mechanical and Process Engineering, ETH Zürich, Zurich, Switzerland
• Video originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in Nature, October 2025