Abstract
Microscale separation is an important process for many medical diagnostics and biological analysis applications. Acoustic based microparticle manipulation has the advantages of low power consumption and good biocompatibility, and has been widely exploited in label-free particle and cell separation. However, typically applied forces scale with increasing particle dimensions, making the selective translation and separation of intermediate-sized objects a multi-stage process. In this work, we realize a single surface acoustic wave (SAW) actuated bandpass filter that can selectively sort out particles with dimensions between smaller and larger diameter populations. This bandpass filter takes advantage of the sharply nonlinear force scaling in the regime where the particle diameter is on the order of the wavelength or larger. Two sets of bandpass filtration, 15.2 mu m polystyrene particles out of 10.2 mu m and 19.5 mu m ones, 10.2 mu m particles out of 8.0 mu m and 11.8 mu m ones, have been experimentally demonstrated. (C) 2016 Elsevier B. V.