Figure 1

Schematic of paper microfluidic RT-LAMP assay. (a) The paper microfluidic chips were designed with SolidWorks and wax-printed on cellulose grade 4 paper. Printed wax patterns were melted and vertically flown through the depth of paper by placing the chips on a hot plate. The dark wax area represents the hydrophobic barrier and the bright area the hydrophilic area where liquid flows. (b) ZIKV-spiked samples of deionized water, tap water (undiluted), human urine (undiluted), or human blood plasma (diluted to 10% with PlasmaLyte), were loaded onto the loading area of a paper microfluidic chip and spontaneously flowed through the channel via capillary action. Contaminants in the sample matrices were filtered during this process, while target RNA flowed at the same speed of bulk liquid. (c) The circular end (detection area) of the paper was cut, and the RT-LAMP reaction mixture was added onto it. This cut-out paper was placed on a hot plate at 68 °C up to 40 minutes to achieve amplification. The color change of the paper is monitored in situ through capturing images with a smartphone.