Paper-Based Microfluidics for Point-of-Care Medical Diagnostics

In the last decade, the chemistry research community has witnessed an explosive growth of microfluidic devices made of paper (paper-based microfluidics). Use of paper as a substrate material brings several attractive features including extremely low cost and auxiliary pump-free liquid transportation, among others, and application of paper-based microfluidics to on-site medical diagnosis has been actively pursued. To meet the demand for medical diagnostic devices operable by end-users without expert knowledge in resource-limited settings, recent studies on paper-based microfluidics pay particular attention to simplification of user operations prior to an assay (e.g. achieving multistep enzymatic assays by single pipetting) and resulting signal readout (e.g. achieving naked eye-based analog thermometer-style result interpretation). One of the objectives of this chapter is to overview state-of-the-art research progresses in simplification of user operational procedures and development of equipment-free signal readout approaches. Moreover, advanced technologies that show the potential to become the next generation of paper-based microfluidics for point-of-care applications are also discussed in this chapter. In addition, the basics of paper-based microfluidics including a short history of paper-based microfluidics, a comparison of paper-based and conventional plastic- or glass-based microfluidic devices and general requirements for ideal point-of-care testing devices are described. The authors believe this chapter helps researchers new to the field and researchers with different backgrounds to learn about analytical applications exclusively achieved by paper-based microfluidics and future challenges in developing “truly” practical medical diagnostic devices.