Particle-Free Extraction by Using Microchannel Structures

Abstract

Modern separation methods of particles are usually prepared by large equipments. In this study, microfluidic chips with backward-facing-step (BFS) microchannel structures and centrifugal force are used to extract particle-free fluid from physical samples at the branch. Numerical simulation and experimental studies were performed to investigate the effects of inlet Reynolds number ( Re 0), as well as the particle-free fluid outlet Reynolds number ( Re 1), on the minimum radius of particles (R) that can be excluded from the particle-free fluid outlet channel. The fraction of the volumetric flow rate of particle-free extraction α (=extraction flow rate/inlet flow rate) was also obtained to evaluate the efficiency of particle-free extraction. Based on the numerical and experimental results, it is found that the design with 90° elbow inlet channel has a better performance than straight inlet channel. In this experiment, 1.0 μm radius of particles can be successfully separated from the fluid, and the volumetric fraction of the extraction flow rate was approximately 1.8% when inlet and outlet Reynolds numbers are 90 and 3.0 respectively.