Controlling the advancement of the liquid front of the nitrocellulose membrane assay under the influence of the centrifugal force on the Lab-on-a-Disc platform

Abstract

Lateral flow immunoassays (LFIs) are ubiquitous point-of-care platforms for chemical and biological tests. They are widely used due to their portability, low cost, fast time of outcome, and absence of the need for presence of highly trained personnel to conduct these tests. One of the ways to enhance the sensitivity of LFIs is by slowing down the flow rate of the analyte through the active sensing area of the test strips (e.g., test line). Some recent developments towards the goal of the improvement of sensitivity of LFIs include placement of the lateral flow assays on the centrifugal microfluidic platforms (so-called Lab-on-discs) where the flow of the analyte through the lateral flow test strip could be sped up or impeded by the centrifugal force applied to the fluid passing through the lateral flow membrane. The finite element analysis (FEA) simulation is performed using ANSYS Fluent software platform and validated by the lateral flow membranes of several pore sizes, from 7 µm to 15 µm, were incorporated onto micromachined discs with integrated microfluidic networks with an accuracy of simulation to be within 15% of experimental values. The present work reports the dependence of the speed of advancement of the liquid meniscus of LFI placed on the Lab-on-a-Disc as a function of the porosity (volumetric fraction of the pores in nitrocellulose or NC membrane), pore sizes, and angular velocity of the spinning disc.