Effect of sample volume on the sensitivity of lateral flow assays through computational modeling

Lateral flow assays (LFAs) are extensively used in qualitative detection because of their convenience, low cost, fast results, and ease of operation. However, the sample volume used in a lateral flow assay is usually determined experimentally. We test and find that the flow velocity is influenced by sample volume, using fluorescent microspheres as label particles, when analyte concentration is fixed in a sandwich LFA. A model is developed based on mass-action kinetics and advection-diffusion-reaction equation, combing the conjugate pad and nitrocellulose membrane. The model shows predictions from 10 to 120 μL, and predicts accurately the experimental results from 50 to 120 μL where the fluid can flow to the test line. Over all, the model can provide predictions over a wide range of sample volumes for sensitivity analysis. On the basis of the model, the sensitivity of the LFA can be improved according to the sample volume added in the experiment.