Microfluidic simulation framework for point-of-care diagnostics: modeling advection-diffusion-reaction transport in lab-on-chip systems

Abstract

Point-of-care diagnostics (POCD) rely heavily on microfluidic lab-on-chip systems, yet their design process is often hindered by trial-and-error prototyping and inconsistent reproducibility. Efficient diagnostic performance requires a clear understanding of how advection, diffusion, and biochemical reactions jointly govern analyte transport at the microscale. This work presents a lightweight numerical framework for modeling solute behavior in microfluidic channels using the advection-diffusion-reaction equation. A finite-difference solver was applied to a 5 mm × 100 ?m channel under physiologically relevant flow conditions, comparing three regimes: diffusion-only, advection + diffusion, and advection + diffusion + first-order reaction. Results show that high Péclet numbers (Pe ? 1000) drive plug-like transport with minimal lateral mixing, while Damköhler numbers near unity (Da ? 1) produce significant axial decay due to reaction kinetics. Visualizations of concentration fields and breakthrough curves demonstrate how Pe and Da directly influence sensor placement, analyte preservation, and diagnostic sensitivity. The framework provides a transparent and computationally efficient tool for early-stage device design, offering practical guidance for optimizing flow control, channel geometry, and capture-surface behavior in lab-on-chip diagnostics.