Flow control in paper-based microfluidic device for automatic multistep assays: A focused minireview

Although lateral flow tests (LFTs) are easy-to-use diagnostics, they have fundamental limitations for sequential multistep assay that can be reduced to a single chemical reaction step. Paper-based microfluidic devices have attracted considerable attention for use in automatic multi-step assays because paper can be an excellent platform to control sequential fluid flow without external equipment. This review focuses on recent developments on how to control flow rate in paper-based microfluidic devices for automating sequential multi-step assays. The aim of this review is to discuss the limitations of LFTs and potential paper-based microfluidic devices for automated sequential multi-step assays in developing countries; and the existing fluidic control technologies for sequential multi-step assays. In addition, we present future challenges for commercialization of paper-based microfluidic devices to perform automatic multi-step assays.