Nature Video

Tiny Robot Fish Could Swim Through the Body Powered by Ultrasound

The video introduces acoustic robotics, where tiny polymer devices are powered solely by ultrasound‑induced bubble dynamics, eliminating wires, batteries, or magnets and opening the door to fully wireless medical microrobots. A thin polymer sheet is laser‑molded with thousands of sub‑millimetre cavities that trap microscopic air bubbles. When an external ultrasonic field is applied, each bubble vibrates at its resonant frequency, generating micro‑vortices that coalesce into a jet propelling the sheet opposite the bubble‑laden side. By arranging bubbles of different sizes along separate fin sections, the researchers create sequential activation as the ultrasound sweeps across frequencies, producing the undulating motion of a stingray‑shaped robot. The team demonstrated the concept in ex‑vivo pig organs, encapsulating the stingray‑bot in a swallowable capsule that dissolves to release the swimmer, and a wheel‑shaped device that rolls along intestinal walls. A soft gripper built from the same principle delicately lifted a live fish, illustrating precise handling without damage. Ultrasound’s ability to penetrate tissue safely underscores the medical relevance. If scaled, these battery‑free, soft robots could enable targeted drug delivery, localized biopsies, or micro‑surgery with minimal patient discomfort, reshaping minimally invasive care and expanding the toolkit for clinicians.