Van Nguyen

Helios Scholar

Rapid point-of-care (POC) biomarker detection is critical in many applications, including infectious disease detection during a pandemic (COVID-19), biothreat detection on a battlefield, toxin detection in food, pesticide detection in agriculture, etc. Two essential traits of POC devices are their high sensitivity and the ability to operate equipment-free. Paper-based lateral flow immunoassay (LFI) is a widely used equipment-free POC platform, but its sensitivity is still limited. Conversely, its counterpart, the vertical flow immunoassay (VFI), is 10 to 100 times more sensitive but requires additional equipment to operate (Devadhasan et al., 2021). Capillary-driven vertical- or other 3D-immunoassays, which combine the sensitivity of VFIs with the equipment-free operation of LFIs, could be promising platforms for rapid POC biomarker detection. To optimize device performance in capillary-driven immunoassays, water imbibition of the porous paper materials must be well characterized and simulated. This study characterizes and simulates the water-wicking of three commonly used paper materials (two cellulose absorbent pads and one nitrocellulose membrane) under different swelling and evaporation conditions. Complex water imbibition behaviors were observed for the three paper materials with different thicknesses. These behaviors were successfully modeled using COMSOL Multiphysics simulations with the Brookes-Corey theory. These findings paved the foundation for designing highly sensitive paper-based capillary-driven POC biosensors.