Experimental studies on controlling dispersion and fluid flow in paper membranes/assays using hydrogel

Abstract

Paper membranes find applications in various fields, including Point-of-Care (POC) diagnostics, separation, filtration, and fluid transport. Still, they are frequently plagued by dispersion-related issues that lead to uneven flow, further affecting sensitivity and specificity, especially in detection assays. Hence, flow control in paper membranes becomes essential to achieving an effective paper-based platform. The present work develops a novel methodology based on adaptive flow regulation to optimize dispersion and flow control. This approach leverages real-time data to measure the controlled flow rates and prevent dispersion using hydrogel across paper-based membranes. Effects of three major parameters, namely mixing speed (100 rpm – 400 rpm), hydrogel concentration (6.45 mg/ml–12.9 mg/ml) for preparing hydrogel, and types of filter paper membranes are investigated in detail. Imaging techniques are applied to capture high-resolution images of fluid behavior on the paper strip surface at various time intervals, and the results are demonstrated in terms of mean intensity as a quantifiable indicator (0−255). It was found that the hydrogel prepared using 400 rpm mixing speed at a specific concentration exhibited significant resistance to the fluid flow with minimal dispersion. Furthermore, the Filter-paper 441 membrane is compared with other filter-paper membranes used in this experiment. Notably, a 43 %-79 % reduction in dispersion was observed for the hydrogel-laden paper membranes. Additionally, the dispersion was largely minimized even when lower concentrations of sodium hydroxide were detected on hydrogel-based paper assays, enhancing its sensitivity. Overall, this research offers a multifaceted solution to reduce dispersion and optimize flow control in paper-based membranes using hydrogel to improve the performance of the paper assays.