Electrochemical paper-based microfluidic devices: A review of separation, flow analysis, and origami-inspired...

Microfluidic paper-based analytical devices (μPADs) have emerged as promising platforms for decentralized and point-of-need analysis because of their low cost, portability, and ease of fabrication. Despite these general features, their analytical performance can be enhanced by incorporating electrochemical detection, which provides rapid, sensitive responses and is readily compatible with miniaturized architectures. This review aims to present a comprehensive overview of electrochemical μPADs, bridging fundamental principles and advanced developments.

This review begins by presenting the paper properties, such as their porous structure and capillary-driven flow capabilities for fluid manipulation. Next, the article introduces fabrication alternatives for electrodes and microfluidic channels, highlighting critical aspects of each technique. To exemplify the versatility of μPADs, the review presents recent advances in device architecture, focusing initially on origami-inspired configurations and integrated separation techniques, such as paper-based chromatography and electrophoresis devices. These configurations expand the analytical scope of μPADs, enabling multiplexing detection with enhanced selectivity. The review also describes μPAD formats inspired by batch-injection analysis and flow-injection analysis systems, demonstrating how classical fluid-handling concepts are being reinterpreted within paper-based microfluidics.

This review introduces innovations in the fabrication of electrochemical μPADs, highlighting the analytical capabilities and versatility of the resulting platforms. Besides consolidating the current state of the art, this work aims to stimulate innovative design strategies and inspire future technological breakthroughs in the microfluidic field.