Dynamics analysis of microparticles in inertial microfluidics for biomedical applications

Inertial microfluidics-based devices have recently attracted much interest and attention due to their simple structure, high throughput, fast processing and low cost. They have been utilised in a wide range of applications in microtechnology, especially for sorting and separating microparticles. This novel class of microfluidics-based devices works based on intrinsic forces, which cause microparticles to migrate laterally and locate at their equilibrium positions. In this article, a comprehensive theoretical formulation is presented for the dynamics of ultrasmall particles in microfluidics-based devices. Explicit expressions are presented for various important forces, which act on a microparticle, such as drag, Magnus, Saffman and wall-induced forces. In addition, the drag coefficient, diffusion phenomenon and Peclet number are formulated. Finally, the influences of particle size, as a crucial parameter, on various intrinsic forces including drag, Magnus and Saffman forces as well as the wall-induced force, are investigated. It is found that the drag, wall-induced and Saffman forces have an important role to play in the dynamics of microparticles in inertial microfluidics while the effects of Magnus force and diffusion can be ignored in most applications.