Swiss Engineers Develop Silent Microdrones Powered by Sound

Engineers from the EPFL MicroBioRobotics Laboratory (MICROBS) have developed a groundbreaking propulsion system that converts sound waves into thrust. The technology is based on acoustic resonators—specifically designed 3D-printed cavities tuned to specific frequencies. When exposed to sound, the air inside the resonators vibrates intensely, creating a directed airflow through a nozzle.

Using this technology, the team created two types of microdrones. The first resembles a miniature rocket with three downward-facing resonators. The second is a rotor design with three blades, each equipped with a resonator. When an ultrasonic signal is applied, the resonators generate thrust, causing the rotor to spin at over 12,000 RPM, enabling the device to hover in the air.

Beyond aerial applications, the team demonstrated the technology's potential in aquatic environments. Their prototype boat uses three resonators: one for forward motion and two for maneuvering. While limited in payload capacity and flight altitude (under 5 mm), experiments confirmed the concept's feasibility. The next step involves scaling the technology to increase payload capacity.

This innovation opens new possibilities for miniature unmanned systems capable of operating in environments where compactness and silence are essential. Potential applications include environmental monitoring, reconnaissance, and even medical uses.