--- title: "No motors or batteries: how EPFL scientists created microdrones powered by sound" description: "🔊 Scientists from EPFL have created microdrones powered by sound! No motors or batteries. The principle is based on Helmholtz resonance: sound is converted into thrust. 🚁 💡 How it works: • A sound wave pumps the resonator. • Asymmetry of flows creates reactive thrust. • Drone weight is only 150 µg! 🚀 Capabilities: • Control via sound frequency. • Movement like a rocket or helicopter. • 3D-printed bodies. #Science #Robotics #EPFL #Technology #Sound" date: 2026-08-15T21:03:18.000Z lang: en url: https://xab.info/en/posts/no-motors-or-batteries-epfl-sound-powered-microdrones tags: [epfl, micro-robots, acoustic-propulsion, helmholtz-resonance, nanotechnology] publisher: "XAB.info" --- # No motors or batteries: how EPFL scientists created microdrones powered by sound ![EPFL microdrones the size of a coin: innovative devices without motors and batteries, powered by sound waves](https://xab.info/media/2026/08/16/mikrodrony-na-zvukovoy-tyage-epfl/mikrodrony-na-zvukovoy-tyage-epfl-1.webp) ## 🎯 Key Points - Engines have been developed that convert sound into thrust without electronics. - The technology is based on Helmholtz resonance and air flow asymmetry. - Flying microrobots weighing 150 µg, controlled by ultrasound, have been created. - Devices can move on the principle of a rocket or a helicopter. In the world of microelectronics and robotics in 2026, engineers continue to seek ways to miniaturize devices, moving away from traditional power sources. A breakthrough that could change the approach to creating microrobots has been made by scientists from the École Polytechnique Fédérale de Lausanne (EPFL). The team has developed unique miniature engines capable of converting sound waves directly into mechanical thrust. The main advantage of this technology is complete independence from electric motors, batteries, and complex onboard electronics, which traditionally act as a "bottleneck" in the creation of micro-devices. ### The physics of sound: from a humming bottle to jet thrust The new technology is based on a fundamental physical phenomenon known as Helmholtz resonance. Many of us have encountered it in daily life: if you blow across the neck of an empty bottle, it begins to produce a sound. Scientists from the MicroBioRobotic Systems (MICROBS) laboratory decided to use this effect in reverse. Instead of sound being a byproduct, it became the source of energy. Researchers created hollow resonators of round and bell-like shapes. The size and geometry of these cavities were mathematically tuned to specific sound frequencies. When a sound wave of the correct frequency acts on the resonator, the air inside the cavity begins to oscillate intensely. This turns a simple hollow structural element into a fully functional acoustic micro-engine. ### The principle of asymmetry: how sound pushes forward The key to generating thrust is the asymmetry of air flows. With each acoustic oscillation, air enters the resonator in a relatively scattered stream but is forced to exit through a narrow opening as a more concentrated and faster jet. Thanks to this, the average momentum of the outgoing flow acquires a clear direction, and the structure receives reactive thrust similar to that generated in rocket engines. This method is fundamentally different from acoustic levitation, where an external sound field holds a passive object. In the new scheme, sound "pumps" energy into a resonator built into the device, and the robot itself generates the driving force. Such cavities can be easily manufactured using 3D printing from plastic, glass, or other materials, making the technology accessible for mass production. ### From boats to flying microrobots To demonstrate the viability of the technology, researchers went from simple models to complex flying vehicles. First, miniature centimeter-sized boats with one, two, or three acoustic resonators were created. Each cavity was tuned to its own frequency in the audible range. By changing the frequency of the signal from an external speaker, engineers could selectively activate different "engines," causing the boat to move forward, turn, or navigate around obstacles. This demonstrated the possibility of programmable autonomous movement without using onboard computers. Then, using three-dimensional nano-printing, the team manufactured flying microrobots. One of the devices, weighing only 150 micrograms, generated upward thrust using acoustic jets, functioning like a tiny rocket. In another design, resonators rotated miniature blades at speeds up to 13,000 revolutions per minute, creating lift on the principle of a helicopter. These devices operated at ultrasonic frequencies inaudible to humans. ### The future of acoustic robotics According to the developers, further miniaturization will allow the creation of flexible robots with multiple resonators. Each of them will be able to respond to its own frequency and independently bend, rotate, or change individual parts of the device under the influence of sound. This opens up prospects for creating micro-fleets capable of penetrating hard-to-reach places for inspection, drug delivery, or data collection in hazardous environments where the use of electricity is impossible or dangerous. ## 🔍 Fact-Check Verification - [Scientists develop sound-thrust microdrones](https://hi-tech.mail.ru/news/153284-uchenye-razrabotali-mikrodrony-na-zvukovoj-tyage/) - Подтверждает основные факты о разработке EPFL и принципе работы. - [Microdrones taught to fly on sound thrust](https://3dnews.ru/1146845/mikrodroni-nauchili-letat-na-zvukovoy-tyage) - Детализирует технические характеристики (150 мкг, 13000 об/мин) и принцип резонанса. ## ❓ FAQ ### Q: How exactly does sound turn into movement? **A:** Sound waves cause air to oscillate inside the resonator. Due to the asymmetry of the design, the air exits as a more concentrated jet, creating reactive thrust. ### Q: Do these drones need batteries? **A:** No, the drones themselves do not have batteries or electric motors. Energy is supplied from the outside in the form of sound waves. ### Q: What is the weight of the created microrobots? **A:** One of the demonstration devices weighed only 150 micrograms.