Vol. 7, Issue 2, Part G (2025)

Microfluidic paper-based analytical devices (µPADs) are valued for their low cost, portability, and ease of use, making them ideal for point-of-need testing. Their flexibility in design enhances usability, allowing rapid detection and analysis using portable tools. µPADs meet critical needs in areas such as environmental monitoring, healthcare, and food safety by offering quick, reliable, and simple testing solutions.

Paper, an abundant and inexpensive cellulose-based material, is ideal for µPADs due to its micro-porous, capillary-like network that enables fluid flow without external pumps or power. These devices are fabricated by creating hydrophilic zones within hydrophobic barriers. The hydrophilic regions facilitate reactions and analysis, while the hydrophobic barriers control fluid movement and separate different test zones.

µPADs have proven particularly useful in clinical diagnostics, where they provide effective alternatives to time-consuming and expensive laboratory methods. Common detection methods include colorimetry, fluorescence, and electrochemistry. Recent advancements combine optical and electrochemical techniques to improve sensitivity and selectivity. Additionally, distance-based detection is emphasized for its instrument-free readouts, minimizing errors especially in low-resource settings.

This review summarizes the key components and principles in µPAD design and fabrication, as well as their broad applications across biological, pharmaceutical, and environmental fields. Their simplicity, speed, low cost, and minimal training requirements make µPADs a promising tool for widespread analytical use.