Two-dimensional particle separation in coupled acoustic-gravity-flow field vertically by composition and laterally by size.

A flow-based separation of particles usually relies on differences in their mobility in the flow direction, which are mostly produced by a physical force. Various properties of particles, typically the size and composition, simultaneously affect their mobility and, therefore, often complicate the result of separation. If these properties are distinguished on different separation axes, well-defined separation should be realized. Two-dimensional separation of particles has been devised by a simple experimental setup based on the acoustic radiation forces and the Stokes drag. A vertical acoustic-gravity field provides the density resolution better than 1%, and a horizontal acoustic-flow field can also resolve particle sizes with the resolution of <1%. Two-dimensional separation based on the compositions and sizes of particles is demonstrated.