Numerical Model for Optimizing the Pore Size of Lateral Flow Assay

Paper-based microfluidic chips have been developed rapidly in the field of point-of-care diagnostics due to their advantages of low cost, large specific surface area and good biocompatibility. However, the transport mechanism within pore structure of paper-based materials on detection performance is elusive. Focusing on the lateral flow assay which is the typical paper-based microfluidic chip, the porous structure of nitrocellulose membrane was simplified as capillary plate channels, and the numerical model coupling capillary flow and reactive transport process was firstly established. The competition mechanism of sample wicking velocity and specific surface area of nitrocellulose membrane on the detection signal generation was investigated. The results showed that increase of the wicking velocity and larger specific surface area of the membrane can enhance the detection signal, and there is an optimal value of the pore diameter for the nitrocellulose membrane to improve the detection sensitivity, which indicates the direction for the design optimization of the nitrocellulose membrane materials.