Electrochemical microfluidic paper-based analytical devices for cancer biomarker detection: From 2D to 3D sensing systems.

ABSTRACT

Microfluidic paper-based analytical devices (µPADs) offer a unique possibility for a cost-effective portable and rapid detection of a wide range of small molecules and macromolecules and even microorganisms. In this line, electrochemical detection methods are key techniques for the qualitative analysis of different types of ligands. The electrochemical sensing µPADs have been devised for the rapid, accurate, and quantitative detection of oncomarkers through two-/three-dimensional (2D/3D) approaches. The 2D µPADs were first developed and then transformed into 3D systems via folding and/or twisting of paper. The microfluidic channels and connections were created within the layers of paper. Based on the fabrication methods, 3D µPADs can be classified into origami and stacking devices. Various fabrication methods and materials have been used to create hydrophilic channels in µPADs, among which the wax printing technique is the most common method in fabricating µPADs. In this review, we discuss the fabrication and design strategies of µPADs, elaborate on their detection modes, and highlight their applications in affinity-based electrochemical µPADs methods for the detection of oncomarkers.