Novel concept of washing for microfluidic paper-based analytical devices based on capillary force of paper substrates

摘要

A novel washing technique for microfluidic paper-based analytical devices (mu PADs) that is based on the spontaneous capillary action of paper and eliminates unbound antigen and antibody in a sandwich immunoassay is reported. Liquids can flow through a porous medium (such as paper) in the absence of external pressure as a result of capillary action. Uniform results were achieved when washing a paper substrate in a PDMS holder which was integrated with a cartridge absorber acting as a porous medium. Our study demonstrated that applying this washing technique would allow mu PADs to become the least expensive microfluidic device platform with high reproducibility and sensitivity. In a model mu PAD assay that utilized this novel washing technique, C-reactive protein (CRP) was detected with a limit of detection (LOD) of 5 mu g mL(-1).