Sound isn’t just for music or communication — it’s becoming a tool for precision manipulation in underwater environments. Researchers have developed a novel metamaterial that allows objects to be moved, rotated, and positioned underwater without any physical contact, using only carefully controlled sound waves.
This breakthrough comes from Dajun Zhang, a doctoral student at the University of Wisconsin-Madison. He presented his findings on May 20 at the 188th Meeting of the Acoustical Society of America and the 25th International Congress on Acoustics.
At the heart of Zhang’s innovation is a metamaterial — a specially engineered structure whose unique properties stem not from its composition, but from its precise geometry. In this case, the surface of the metamaterial features a sawtooth-like pattern, enabling it to interact with sound in extraordinary ways.
When targeted by ultrasonic speakers, the metamaterial reflects sound waves at specific angles and strengths. By altering the characteristics of the sound, Zhang can generate different acoustic radiation forces, allowing him to push, pull, and rotate objects attached to the material with remarkable accuracy.
“We can apply multiple force vectors remotely, with no contact, in liquid environments,” Zhang said. “This could change how we perform tasks underwater — or even within the human body.”
The ability to manipulate objects remotely in water has far-reaching implications:
- Underwater robotics and vehicles: Position parts or tools in delicate operations without disturbing the environment.
- Medical devices and drug delivery: Use sound to steer tools or medications within the human body, which is largely composed of water.
- Remote surgery: Control surgical instruments or patches internally without invasive procedures.
Creating such finely tuned metamaterials for underwater use has been a persistent challenge — traditional methods lack the resolution, durability, or affordability needed for practical applications. Zhang addressed this by developing a new fabrication process that is low-cost, high-resolution, and achieves the high acoustic impedance contrast with water required for precise control.
“This method is scalable and practical,” Zhang noted. “It enables us to make functional metamaterials suitable for both lab experiments and real-world deployment.”
In experimental tests, Zhang used his metamaterial to control a variety of materials — wood, wax, plastic foam — both floating and fully submerged. Once attached to the metamaterial patch, each object could be moved in three dimensionsusing sound alone, without physical touch or mechanical assistance.
Looking forward, Zhang plans to develop smaller, more flexible metamaterial patches that can be applied in biomedical settings or incorporated into underwater robotic systems.
“Our research opens new doors for acoustic-based manipulation technologies,” he said. “We can now envision a future where sound waves power remote movement for medical, industrial, or environmental applications — no contact required.”
By Impact Lab
