Optimization studies of liquid diffusion interaction for fabrication of paper-based microfluidic sensing device

Abstract

Simple, low-cost and rapid sensing devices are in urgent demand for diagnostics purposes especially in resource-limited areas. Devices fabricated from patterning paper into hydrophilic and hydrophobic regions named as paper-based microfluidic analytical devices (μPADs) have been introduced. One of important parameter in the operation of μPADs is the fluid control. This project focused on the experimental and theoretical investigation of liquid flow rate analysis on μPADs. In the experimental part, the factors that affect the flow rate of liquid inside the channel have been investigated including the design of channel which is cut and wax channel, the platform of liquid flow which is in horizontal and vertical flow and the liquid viscosity. In the theoretical part, the pore size of paper have been investigated. In this project, straight line handcrafted channel at dimension of 3 mm width have been fabricated on 3 types of paper which is filter paper grade 1, chromatography paper grade 1 and blue litmus paper. 10 different viscosities of sucrose solutions ranging from 0 to 70 % of sucrose solute with the additional of 2 blind test samples have been tested on wax and cut channel with horizontal and vertical flow in a minute. The flow rate is then calculated using volumetric flow rate equation. In the theoretical part, the flow rate is calculated in MATLAB using Washburn equation and Darcy’s law equation. In summary, it can be concluded that the horizontal liquid flow in cut channel have higher flow rate compared to vertical liquid flow in wax channel. Furthermore, high viscous liquid slow down the liquid flow in the channel. For the selection of paper, it is advisable to choose filter paper as the paper materials in the fabrication of μPADs compared to chromatography paper and litmus paper.