Acoustic angular sorting of resonant subwavelength particles

We suggest a dynamical mechanism for angular sorting of subwavelength particles in accord with their resonances and sizes, realised with the forces imposed by acoustic (ultrasound) waves with different wavelengths. We analyse how the acoustic force acting on a small particle depends on its size relative to the ultrasound wavelength, and how the detuning between the two different beams influences the size range and angular distribution for unambiguous sorting outcomes for a given size range. We predict a range of scenarios depending on the particular materials and provide several feasible examples and discuss their practical realisation.