Rapid Diagnostics using Microfluidic PaperBased Assays

Abstract

Microfluidic paper-based analytical devices (µPADs) have emerged since the late 2000s as a transformative platform for rapid, low-cost diagnostic assays—especially suited to resource-limited settings. Harnessing capillary action within paper substrates, these devices enable fluid transport without external pumps, allowing multiplexed detection of biomarkers with simple fabrication and portability. The pioneering 2007 work by Whitesides’ group introduced 3D stacked-pattern µPADs capable of executing multiple assays concurrently. Subsequent advances incorporated hydrophobic channel patterning via wax printing, inkjet techniques, and photolithography, facilitating reliable flow control. Detection modalities have evolved from simple colorimetric tests (e.g., glucose, proteins, pH) to quantitative readouts using electrochemical and fluorescent approaches. Notably, device fabrication remains inexpensive and accessible, with some prototypes costing just a few cents. Paper-based diagnostics also meet several of the World Health Organization’s ASSURED criteria—Affordable, Sensitive, Specific, Userfriendly, Rapid and robust, Equipment-free, and Deliverable. However, challenges remain in scaling up production, enhancing flow control, quantification, and ensuring regulatory compliance. This paper reviews foundational developments in µPAD design and application before 2018, presenting their advantages, limitations, and deployment potential. Through critical synthesis, we propose methodological insights and suggest that integrating advanced detection methods and improved channel design could accelerate real-world adoption of µPAD platforms in global health diagnostics.