Acoustic Standing-Wave Field for Manipulation in Air

A noncontact manipulation technique is necessary in micromachine technology. Using a standing-wave field generated between a transducer and a reflector, it is possible to trap particles at nodes of a sound pressure field. In the present paper, a sound filed has been studied by both experimental measurement and numerical caluclation. The sound pressure distribution of a standing-wave field was measured using a small microphone and calculated numerically using Rayleigh's formula. Although Rayleigh's formula is usually used to calculated direct sound pressure from a sound source, it has been shown that the sound pressure of the standing-wave field can be calculated by Rayleigh's formula by addding multiply reflected waves. [DOI: 10.1143/JJAP.47.4336]