Parametric Analysis of Wax Printing Technique for Fabricating Microfluidic Paper-Based Analytic Devices (µpad) for Milk Adulteration Analysis

Accurate prediction of hydrophobic–hydrophilic channel barriers is essential in the fabrication of paper-based microfluidic devices. This research presents a detailed parametric analysis of wax printing technique for fabricating µPADs. Utilizing commonly used Grade 1 filter paper, experimental results show that the wax spreading in the paper porous structure depends on the initially deposited wax line thickness, a threshold melting temperature and melting time. Initial width of the printed line has a linear relationship with the final width of the barrier; however, a less pronounced effect of temperature was observed. Based on the spreading behavior of the molten wax at different parameters, a generalized regression model has been developed and validated experimentally. The developed model accurately predicts wax spreading in Whatman filter paper: a non-uniform distribution of pores and fibers. Finally, tests were carried out for calorimetric detection of commonly used adulterants present in milk samples.