Silent Drones: Researchers Develop 3D-Printed Sound-Powered Jet Engines

Micro drones have long been a subject of interest in the tech world, but one major drawback has always been their noise level. However, a team of researchers from Switzerland's École Polytechnique Fédérale de Lausanne (EPFL) Microbiorobotic Systems Laboratory (MICROBS) has made a breakthrough in developing a 'sound-powered engine' that uses 3D-printed cavities and ultrasonic frequencies to propel micro drones completely silently. The researchers used a specially shaped 3D-printed cavity to create an acoustic resonator that harnesses sound at specific frequencies to generate directional thrust and controlled motion. This resonator is then used to propel the air molecules inside the cavity, which are pushed out of a specially designed nozzle as a concentrated jet. The team has created three practical applications of the 'engine,' including a boat that uses three resonators for propulsion and navigation, and two microfliers powered by ultrasonic frequencies. The first microflier has three cavities facing downward, allowing it to lift off the ground like a rocket, while the second flier has three blades connected at a central point, with the base of each blade equipped with a resonator pointing backward. When the resonators are hit with the exact frequency that drives them, they deliver thrust that allows the second flier to rotate at over 12,000 rpm and hover. The use of ultrasonic frequencies makes these devices practically noiseless, as they are inaudible to humans. While the team has successfully used the 'sound-powered engine' for experiments, the microfliers' maximum altitude is less than 5mm, and the boat weighed next to nothing. However, now that they've proven that the concept works, the next step is to scale it up to carry payload. If they can make it work, it could potentially be used as propulsion for micro-drones, like the mosquito-sized unit from China. The development of the 'sound-powered engine' is an exciting breakthrough in the field of micro-drones, and it has the potential to revolutionize the way we think about drone technology. However, it remains to be seen whether the team can successfully scale up the technology to make it practical for real-world applications. ## The Science Behind the 'Sound-Powered Engine' The 'sound-powered engine' works by harnessing the power of sound waves to propel air molecules inside a specially shaped 3D-printed cavity. The cavity is designed to resonate at specific frequencies, which are then used to generate directional thrust and controlled motion. This is achieved by pushing the air molecules out of a specially designed nozzle as a concentrated jet. ## The Potential Applications of the 'Sound-Powered Engine' The 'sound-powered engine' has a wide range of potential applications, from micro-drones to boats and other vehicles. The technology has the potential to revolutionize the way we think about propulsion systems, and it could potentially be used in a variety of fields, including search and rescue, surveillance, and environmental monitoring. ## The Next Steps for the 'Sound-Powered Engine' While the team has successfully developed the 'sound-powered engine,' there is still much work to be done before it can be used in real-world applications. The next step is to scale up the technology to make it practical for carrying payload, and to test its performance in a variety of environments. If the team can successfully achieve this, it could potentially be used as propulsion for micro-drones, and it could have a major impact on the field of drone technology.