Simulation study on liquid percolation in diffusion layer of in-vitro diagnostic chips

Abstract

In-vitro diagnostic chips were used to achieve point-of-care testing for its advantages including rapidity, convenience, and accuracy. Diffusion layer in multi-layer structure of in-vitro diagnostic chips integrate multiple functions, including even dispersion of the liquid and high reflectivity. However, few studies of liquid percolation in the diffusion layer have been reported. In this paper, Lattice Boltzmann Method was used to simulate the process of liquid percolation in diffusion layer of in-vitro diagnostic chips. Effects of microsphere material, microsphere diameter, and liquid type (serum or water) on percolation were investigated. The results showed that all the 3 factors had increasing degree of influence on liquid percolation in diffusion layer. Based on these simulations, it was found that a particle diameter of 4 ∼ 6 μm, liquid kinematic viscosity of 0.89 × 10−6∼1.37 × 10−6 m2/s, and microsphere contact angle of 30.5 ∼ 40.5° were conducive to controlling the percolation process in chip diffusion layer. Thus, Lattice Boltzmann Method can be nominated to explore the percolation laws in diffusion layer of in-vitro diagnostic chips. Further simulation studies should provide the basic data required for the development of multi-layer in-vitro diagnostic chips, which helps chip designers to select appropriate materials and particle diameter.