EPFL 3D Nanoprints Sound-Powered Microfliers That Fly Without Motors

No Motors, Just Sound

Engineers at EPFL have built tiny flying vehicles that need no battery, no motor, and no electronics. Instead, they fly on sound. Using 3D nanoprinting, the team integrated microscopic acoustic cavities directly into polymer structures. When hit with the right frequency, those cavities spit out focused jets of air, generating enough thrust to lift the craft off the ground.

The work comes from the MicroBioRobotic Systems Lab in EPFL's School of Engineering. It was published in Science Advances on August 14, 2026.

How the Thrust Works

The secret is Helmholtz resonance. You have heard it when you blow across the top of a glass bottle. The air inside the cavity vibrates at a specific frequency, producing a tone. The EPFL team turned that physics into propulsion. When sound waves excite the air inside a hollow cavity, the oscillating air exits as a concentrated jet. The incoming airflow is more spread out. That imbalance creates net thrust in one direction.

The cavities can be 3D printed from common plastics, rubber-like polymers, or glass. That flexibility means the approach scales across materials and manufacturing methods.

Two Microflier Designs

The team built two flying designs, both weighing just 150 micrograms. The first uses three downward-facing cavities. At ultrasonic frequencies, the cavities fire in sequence, lifting the microflier straight up like a rocket. The second design attaches a tiny rotor to the body. Each blade carries a resonator pointing backward. When the ultrasonic signal hits the exact resonant frequency, the blades spin at up to 13,000 revolutions per minute, holding the craft aloft like a helicopter.

Because ultrasonic frequencies are inaudible to humans, the hovering craft is essentially silent.

Boats That Steer Themselves

At a larger scale, the team printed centimeter-long boats carrying up to three cavities. Each cavity is tuned to a different audible frequency and angled to push the boat in a specific direction. By changing the speaker frequency, the operators can activate individual cavities, steering the boat around obstacles or programming it for autonomous paths. The researchers even directed one boat to trace the letters E-P-F-L across a small pool.

Why It Matters

Removing motors, gears, and batteries shrinks the mechanical complexity of small robots dramatically. These devices rely on geometry, not components. The team sees potential in search-and-rescue micro-robots, environmental sensors, or biomedical devices that need to move through confined spaces. The next step is scaling the design to carry small payloads.

The paper is open access: Junsun Hwang et al., "Acoustic resonators as wireless actuators in air for small-scale robots," Science Advances, August 2026.