{"id":116464,"date":"2026-08-17T13:40:32","date_gmt":"2026-08-17T13:40:32","guid":{"rendered":"https:\/\/www.europesays.com\/ch\/116464\/"},"modified":"2026-08-17T13:40:32","modified_gmt":"2026-08-17T13:40:32","slug":"swiss-researchers-built-tiny-drones-powered-by-sound-using-40-khz-ultrasound-and-3d-printed-resonators-to-generate-thrust","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ch\/116464\/","title":{"rendered":"Swiss researchers built tiny drones powered by sound, using 40 kHz ultrasound and 3D-printed resonators to generate thrust"},"content":{"rendered":"

\"SwissPC: The MicroBioRobotic Systems Lab’s microfliers. 2026 EPFL\/MICROBS – CC-BY-SA 4.0 2026 EPFL\/MICROBS – CC-BY-SA 4.0 A tiny flying machine does not necessarily need a motor to get off the ground. Engineers at the Swiss Federal Institute of Technology in Lausanne (EPFL) have demonstrated microfliers that use sound to generate the force needed for flight, replacing conventional propulsion with carefully designed hollow cavities. The devices rely on Helmholtz resonance, the same acoustic effect familiar when blowing across a bottle. When exposed to the right frequency, air inside the cavities moves rapidly through their narrow openings, creating small but usable jets of air. The team built one microflier weighing just 150 micrograms and another weighing 184 micrograms, with the latter reaching about 13,000 revolutions per minute. According to the paper published in Science Advances, titled \u2018Acoustic resonators as wireless actuators in air for small-scale robots<\/a>\u2019, it also showed that sound can control miniature boats and select different directions of movement. The results offer a way of powering machines at scales where fitting conventional motors and batteries becomes increasingly difficult.<\/p>\n

How Helmholtz resonance helps tiny drones generate thrust<\/p>\n

The basic idea comes from Helmholtz resonance, the same effect responsible for the tone produced when air is blown across the opening of a bottle. A resonator consists of an enclosed air cavity and a narrow neck. When sound reaches the structure at its natural frequency, the air in the neck oscillates strongly. The movement is not perfectly symmetrical, and that imbalance produces a concentrated jet of air. The resulting momentum can push the resonator in the opposite direction. The Swiss Federal Institute of Technology in Lausanne (EPFL) shaped this effect into tiny mechanical actuators rather than treating sound as a force that simply carries an object along. Their resonators were produced at scales ranging from centimetres to micrometres, with operating frequencies spanning roughly 200 Hz to 40 kHz. The measured resonance frequencies were within 5 per cent of the researchers’ theoretical predictions. The structures turn basic cavities into \u201cwirelessly powered actuators\u201d.The geometry matters. The size of the cavity affects its resonant frequency, while the neck has a particularly strong influence on the thrust. Tests showed that thinner neck walls could produce greater thrust, while changing the overall shape of the cavity had comparatively little effect at the small scales tested. The team also found that resonators could be made from a wide range of materials, including glass, PLA, and soft elastomers, without losing their ability to generate useful thrust.\"How<\/p>\n

Image AI generated<\/p>\n

Sound-powered miniature boats can move, turn and avoid obstacles<\/p>\n

The researchers first demonstrated the concept with miniature boats. A boat fitted with a single resonator could move when exposed to its designated frequency. More elaborate versions carried three resonators, each tuned differently. One provided forward motion, while the other two were used for turning. By changing the sound frequency, the researchers could therefore select which part of the boat produced thrust. That made the sound field a form of remote control. The boat could be directed along a predefined path, including an infinity-shaped trajectory, and could manoeuvre around obstacles. A separate experiment used two resonators with different frequencies to produce reversible forward and backward movement. The work also showed that the propulsion came from the resonators themselves rather than simply from the sound field pushing the boats.The approach was taken a step further with structure-borne sound, where a small transducer is attached directly to the resonator rather than relying entirely on a speaker positioned outside the machine. That arrangement allowed the researchers to build an untethered boat carrying its own battery, electronics and vibration actuators. It was able to trace the letters \u201cEPFL\u201d and navigate around obstacles. The researchers also demonstrated automated movement using programmed sequences of frequencies.<\/p>\n

How Swiss researchers used ultrasound to make tiny drones fly<\/p>\n

The most striking part of the work came when the resonators were shrunk to the microscale. Using two-photon polymerisation, a high-resolution 3D printing method, the team produced a microflier weighing about 150 micrograms. Three microscopic resonators were built directly into its polymer structure and tuned to 40 kHz, above the normal range of human hearing. The device was tested with a 16-by-16 ultrasonic phased array containing 256 transducers. Concentrated ultrasound generated the resonators’ air jets and gave the microflier enough upward force to leave its support. At the tested acoustic pressure, each resonator produced an estimated 2.4 micronewtons of thrust, giving the three-resonator machine a thrust-to-weight ratio of about 4.9. The flier accelerated rapidly after activation, reaching a peak of around 30 metres per second squared during its initial take-off.A second design used the same basic acoustic principle differently. Instead of directing the thrust straight down, the resonators were connected to tiny rotor blades. Once excited, the structure spun rapidly enough for the blades to generate aerodynamic lift. This microflier weighed about 184 micrograms and reached approximately 13,000 revolutions per minute. The researchers observed that the rotating design produced more stable flight than the version relying on direct vertical thrust, which sometimes flipped during unconstrained flight.<\/p>\n

Future of tiny drones powered by sound and acoustic resonators<\/p>\n

The work does not mean that sound-powered drones are ready to replace conventional aircraft or miniature motors. The experiments point instead to a possible route for building machines at scales where batteries, motors and other conventional components become increasingly difficult to integrate. The researchers’ own results show that the acoustic structures can be made extremely small, but they also identify physical limits that become more important as the dimensions shrink. For the airborne microfliers, one immediate constraint is the external equipment. Strong, precisely controlled ultrasound has to be maintained around the flying device, and the useful workspace is therefore tied to the acoustic and imaging systems. Putting the source of vibration on the robot avoids that dependency, but then the transducer, battery and control electronics must all fit within an extremely small mass budget. The paper describes this as a substantial practical challenge.These are imposed fluid dynamics. At still smaller dimensions, viscous effects become increasingly important and can dissipate energy through the thin boundary layers around the moving air. The simple relationship between resonator size and thrust may therefore stop holding at sufficiently small scales. The researchers suggest that future systems could use several frequencies at once, allowing different resonators to be activated selectively for steering and coordinated movement. For now, the experiments establish something more basic: a hollow printed cavity, when tuned correctly, can take energy from sound and turn it into mechanical motion.<\/p>\n","protected":false},"excerpt":{"rendered":"PC: The MicroBioRobotic Systems Lab’s microfliers. 2026 EPFL\/MICROBS – CC-BY-SA 4.0 2026 EPFL\/MICROBS – CC-BY-SA 4.0 A tiny…\n","protected":false},"author":2,"featured_media":116465,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_share_on_mastodon":"0"},"categories":[4],"tags":[56707,56708,10451,56709,56712,56711,56516,41,56710,56713,17,56714],"class_list":["post-116464","post","type-post","status-publish","format-standard","has-post-thumbnail","category-switzerland","tag-3d-printed-resonators","tag-acoustic-resonators","tag-epfl","tag-micro-sized-robots","tag-miniature-boats","tag-science-advances","tag-sound-powered-drones","tag-swiss","tag-swiss-federal-institute-of-technology","tag-swiss-federal-institute-of-technology-in-lausanne","tag-switzerland","tag-tiny-drones"],"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ch\/117111136515142211","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts\/116464","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/comments?post=116464"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/posts\/116464\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/media\/116465"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/media?parent=116464"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/categories?post=116464"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ch\/wp-json\/wp\/v2\/tags?post=116464"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}