Numerical Investigation of the Coulter Principle in a Hydrodynamically Focused Microfluidics

Abstract

 Abstract—A numerical method is proposed to study the Coulter principle in a microfluidics where low-conductive suspended cells and a high-conductive sample stream are hydrodynamically focused by two low-conductive sheath streams. The diffusion phenomenon of the high-conductive sample stream was modeled by solving a convection-diffusion equation. The motion of the suspended cell was calculated by solving the coupled equations of motion and the Navier-Stokes equations. The electric field was calculated by solving the Laplace's equation. With the proposed method, the effects of cell size, electrode size and electrode position, and the sheath flow width on the measured signal variation were systematically studied. Our simulations showed that fluid diffusivity plays an important role in determining the signal variation. We also showed that the current sensitivity increases with the cell size and the electrode size but it decreases with the sheath flow Index Terms—Coulter principle, computational fluid dynamics, hydrodynamic focusing, current sensitivity