Scientists can levitate and move objects using only high-frequency sound waves.

Acoustic levitation relies on standing waves created when an acoustic transducer and reflector are precisely aligned. As sound waves bounce between these components, they interfere with each other to form nodes—points of zero pressure—and antinodes—points of high pressure. Small objects and liquid droplets become trapped at the nodes because the acoustic radiation pressure counteracts gravity.The technology typically employs ultrasonic frequencies above 20 kilohertz, which are inaudible to humans but powerful enough to lift matter. In 2013, researchers at ETH Zurich achieved a landmark breakthrough by successfully moving and merging droplets in mid-air using a phased array of transducers. This demonstration proved that objects could not only be held stationary but also precisely manipulated in three-dimensional space.NASA and other space agencies have adopted containerless processing to study materials without contamination from holding vessels. This approach is particularly valuable for pharmaceuticals, where contact with glass can trigger unwanted crystallization. Modern systems can now levitate objects denser than water—such as lead or electronic components—by increasing the ultrasonic field intensity.Beyond laboratory demonstrations, this technology is being integrated into microfluidics and chemistry labs worldwide. It enables observation of chemical reactions in a pure environment, unaffected by container walls. As the technology matures, scientists aim to apply it to non-invasive medical procedures and the assembly of complex micro-scale structures.