Expanding channels enhanced diffractive SAW actuated particle enrichment in vacuum-sealed microfluidic channels

Abstract

Diffractive surface acoustic wave (SAW) methods have recently emerged as a promising approach for bioparticle manipulation and enrichment, with advantages in flexibility and ease of alignment compared to standing-wave SAW based micromanipulation. Here we demonstrate a diffraction-based focusing approach based on an expanding channel that multiplicatively improves enrichment efficiency. Uniquely, this permits the generation of particle enrichment across several acoustic wavelengths, where particles are first focussed along channel walls, with the cross-section of the flow subsequently being arbitrarily expanded. We numerically and experimentally validate the generated pressure fields across t..