Round cavity-based vortex sorting of particles with enhanced holding capacity

Abstract

The sorting of target particles from heterogeneous samples is challenging yet crucial for cell biology research and clinical diagnosis. Among various microfluidic methods, the use of cavity-based laminar vortex combined with inertial focusing is a powerful label-free passive technique for the selective sorting of large rare cells with high purity and concentration from billions of blood cells. However, this technology faces the challenge of improving the cavity holding capacity of trapped particles. This paper describes a round cavity-based vortex sorting method and presents a novel judgment criterion. The proposed round cavity achieves a holding capacity of entrapped target particles that is 2.2-7.8 times higher than that of rectangular cavities. By comparing the particle recirculating orbits and the simulated vortex morphology in round and rectangular cavities, a mechanism whereby particles/cells are held within the cavities is investigated. It is found that the area ratios (S = Ap/Ac) of the particle orbit area (Ap) to the cavity area (Ac) are 0.56 and 0.95 for the rectangular and round cavities, respectively. The results show that the round cavity provides more efficient space for recirculating particles and has better sorting performance. This round cavity-based vortex sorting method will be useful for clinical applications.