Characteristics of Microfluidic Paper-based Analytical Devices Fabricated by Four Different Methods

We report on the effects of fabrication methods, photolithography, wax printing, screen printing, and craft cutting, on selected properties of microfluidic paper-based analytical devices (mu PADs): cost, fabrication precision, wicking rate, and analytical accuracy. Photolithography requires numerous fabrication steps, and an oxygen plasma treatment is necessary when using an aqueous solution. Although the boundary between the hydrophobic and hydrophilic areas in the mu PAD is sharpest, the obtained K-scale intensity in measuring of protein concentrations is lower than those of the devices by other methods. Wax printing offers the simplest and fastest fabrication, although solution leakage measures should be taken to improve the wicking rate and to prevent cross-contamination. Screen printing also offers easy fabrication. The screen printed mu PAD has a good wicking performance and shows a high detection intensity. Craft cutting allows automated fabrication of many mu PADs at once. The craft cut mu PAD has the fastest wicking rate among the four mu PADs due to bare cellulose fibers. We consider that the detection intensity of this mu PAD can be raised by optimizing the evaporation rate.