# Numerical and Experimental Analysis of Microparticle Focusing and Separation in Split–Recombination Microchannel

## TL;DR

This paper presents a simple microfluidic device that uses inertial forces to focus and separate microparticles efficiently for biomedical and environmental applications.

## Contribution

A novel split–recombination microchannel design is introduced for passive microparticle focusing and separation using inertial lift and Dean drag forces.

## Key findings

- Microparticles migrate laterally and form two narrow streams in the microchannel.
- The focusing effect improves significantly with an increase in the channel angle.
- Separation of two microparticle sizes was successfully demonstrated experimentally.

## Abstract

Inertial microfluidics has obtained attention for its good performance in microparticle manipulation. It has the advantages of simplicity, high throughput, and a lack of external fields. In this paper, a simple microfluidic device is described, which contains several split and recombination structures. The design takes advantage of microparticle migration based on inertial lift and the Dean drag force. Two forces drive microparticles to move laterally and arrive at equilibrium positions in a split–recombination microchannel. Based on the numerical and experimental analysis, the trajectories of microparticles are described, and microparticles are focused and form two narrow streams. In addition, the focusing of microparticles is enhanced significantly with the increase in angle. Finally, two sizes of microparticles are separated in experiments. The simple device and high throughput offered by this passive microfluidic approach make it attractive in biomedical and environmental applications.