Daily Weird News Report
A new acoustic levitation system can hold and manipulate small objects in midair from a single direction, including at distances of up to 40 centimeters from its sound source, according to research published in Physical Review Letters.
The method was developed by researchers from the University of Tsukuba in Japan and the University of Bristol. It uses an ultrasonic phased array to produce a zero-order Bessel beam, a type of sound beam whose narrow, high-intensity central region remains concentrated over a longer distance than a conventional beam.
Acoustic levitation suspends objects without physical contact by using sound waves. Conventional systems generally stabilize an object with sound coming from opposing directions inside an enclosed arrangement. Earlier single-sided designs had a more limited working range because the holding force weakened as an object moved away from the source.
In the reported demonstration, the researchers stably levitated a polystyrene sphere measuring 1.5 millimeters in diameter at distances ranging from 141 to 397 millimeters. The maximum distance was approximately six times farther than previously achieved with single-sided acoustic traps, according to the report.
The team also manipulated the levitated object in three dimensions. The reported experiments included multiple objects, non-spherical objects and objects positioned beyond other physical objects. The system’s sound field was described as extending along the beam’s axis, allowing the trap to operate in an open environment rather than relying on sound waves arriving from opposite sides.
The researchers said the technique could eventually support noncontact handling of fragile or contamination-sensitive materials, hazardous substances, automated experiments and three-dimensional displays. Those are proposed applications rather than demonstrated uses in the study.
The work is described in the paper “Midair Single-Sided Acoustic Levitation in High-Pressure Regions of Zero-Order Bessel Beams,” by Yusuke Koroyasu and colleagues. The report identifies the 40-centimeter result as the longest distance achieved in the described single-sided acoustic levitation approach.
