Levitation and Control for an Ordered Group of Particles and Rectilinear Structures in an Ultrasonic Field

Abstract

A method of control for an ordered group of particles that levitate in an ultrasonic field and structures of rectilinear segments is proposed. An ultrasonic field in air at a frequency of 40 kHz and particles whose dimensions are less than a quarter of a wavelength or thin cylindrical objects with diameters of less than a quarter of a wavelength are considered. The ultrasonic field is formed using four phased arrays of radiators that are placed oppositely on lateral faces of a rectangular parallelepiped. The radiators form a distribution of the standing wave field in the plane, which provides levitation of particles in a rectangular grid in a plane layer. With the use of numerical simulation and experimentally, it has been shown that the obtained distribution is stabilized and the particles remain immobile at local minimums of the Gor’kov potential. Moreover, regulation of the phase difference of opposite radiators provides controlled motion of a group of particles in a horizontal plane and a change in the focusing plane of side radiators provides controlled motion of a group of particles along the vertical plane. It has been shown experimentally that not only small particles but also structures assembled of rectilinear segments whose length is much greater than the wavelength can levitate in this field distribution.