Manufacturing of a Point-of-Care Paper-Based Microfluidic Device for Diagnosing Diabetes Mellitus in In-Developing Countries
Authors:Mary Arrastia, Giorgio Gianini Morbioli, Ana Carolina Rafanhin
- Frank Gomez, Professor of Chemistry, California State University, Los Angeles
- Emanuel Carrilho, Professor of Chemistry, Universidade de São Paulo – São Carlos
In many in-developing countries, the cost to test for diabetes mellitus, more commonly known as diabetes, is expensive, and half of those with diabetes are left undiagnosed. This research has focused on creating an optimal, cost-effective paper-based microfluidic device (μPAD) to quickly test for diabetes in fasting subjects by measuring mean color intensity outputs versus salivary glucose concentrations. While there is currently no well-defined range for diabetes using salivary glucose concentrations, previous studies have correlated those with blood glucose concentrations in the diabetic range with high concentrations of glucose in saliva. Single channel and multi-channel designs were made on CorelDRAW X6 and printed on Whatman Grade 1 Chromatography paper using a Xerox Phaser 8560 wax printer. The cost of fabricating a μPAD is very low, considering that Whatman chromatography paper is about $0.001/cm2 and solid ink is about $0.0001/cm2. The final design has incorporated a multiplex design with 4 channels angled at -75°, -25°, 25°, and 75° from normal, respectively. The printed designs were hot pressed to allow for the wax to bleed through the paper to create a hydrophobic barrier for the channel. The channels were spotted with a 5:1 solution of glucose oxidase to horseradish peroxidase and were left to dry for 5 minutes before taping front and back sides of the μPAD to control evaporation during testing. Various glucose solutions in artificial saliva were made at concentrations between 5 x 10-4 g/mL to 0.1 g/mL. The color intensities were measured and averaged in each channel. There were no significant differences in the color intensities in each channel (p>0.05), and a linear range of concentrations was found between 5 x 10-4 g/mL and 5 x 10-3 g/mL, which is one order of magnitude higher than the level seen in diabetic patients as discussed by Sener et al., 2009.