Fast and highly efficient multiplexed electrokinetic stacking on a paper-based analytical device

Abstract

A microfluidic paper-based analytical device (PAD) with both pre-concentration and parallel operation functions is of great promise for sensitive and high throughput detection. In this paper, a fast and multiplexed PAD was designed based on wax-screen-printing with glass fiber paper substrate and validated by image-based colorimetry. Driven by the same DC power supply, parallel electrokinetic stacking with the PAD of 8 channels can be completed within 2 min, and each channel can be loaded with different samples. Enrichment factor of 2 orders of magnitude was demonstrated with RSD below 2.5% between the chips and the channels of a chip. Reproducible and multiplexed stacking operations of this PAD provide a solid foundation for online calibration and sample detection on the same chip at the same time. Applications of this PAD was demonstrated by online colorimetric detection of food pigments from beverages and offline MS/MS detection of amino acids from a serum sample. Besides high-throughput and sensitive point-of-care test detection, this PAD method could also find applications for efficient pre-separation and pre-concentration of complex samples.