Figure 2. The patterning frequencies in comparison with previous acoustic trapping work.

The bulk of research in acoustic microfluidics has focussed on the limiting case where the particle diameter is substantially less than the acoustic wavelength, with and f∝λ⁻¹, with typical frequencies of 1–50 MHz. Here, individual particles can be separated in individual acoustic force minima through the imposition of higher ratio of D/λ, a regime accessible due to the higher absolute frequencies utilized here, in the range of 100–230 MHz. The OCPW regime, which delineates the permissible D/λ and absolute values of λ, for trapping of cells (1 μm<D<20 μm) is encompassed by the dotted line shown.