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Paper Stacks for Uniform Rehydration of Dried Reagents in Paper Microfluidic Devices

Das, Debayan and Dsouza, Andrea and Kaur, Navjot and Soni, Shruti and Toley, Bhushan J (2019) Paper Stacks for Uniform Rehydration of Dried Reagents in Paper Microfluidic Devices. In: SCIENTIFIC REPORTS, 9 (1).

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Official URL: https:/dx.doi.org/10.1038/s41598-019-52202-9


Spatially uniform reconstitution of dried reagents is critical to the function of paper microfluidic devices. Advancing fluid fronts in paper microfluidic devices drive (convect) and concentrate rehydrated reagents to the edges, causing steep chemical gradients and imperfect mixing. This largely unsolved problem in paper microfluidics is exacerbated by increasing device dimensions. In this article, we demonstrate that mixing of dried reagents with a rehydrating fluid in paper microfluidics may be significantly enhanced by stacking paper layers having different wicking rates. Compared to single-layer paper membranes, stacking reduced the ``non-reactive area'', i.e. area in which the reconstituted reagents did not interact with the rehydrating fluid, by as much as 97% in large (8 cm x 2 cm) paper membranes. A paper stack was designed to collect similar to 0.9 ml liquid sample and uniformly mix it with dried reagents. Applications of this technology are demonstrated in two areas: (i) collection and dry storage of sputum samples for tuberculosis testing, and (ii) salivary glucose detection using an enzymatic assay and colorimetric readout. Maximizing the interaction of liquids with dried reagents is central to enhancing the performance of all paper microfluidic devices; this technique is therefore likely to find important applications in paper microfluidics.

Item Type: Journal Article
Additional Information: copy right of this article belong to NATURE PUBLISHING GROUP
Department/Centre: Division of Mechanical Sciences > Chemical Engineering
Date Deposited: 10 Dec 2019 05:42
Last Modified: 10 Dec 2019 05:42
URI: http://eprints.iisc.ac.in/id/eprint/63958

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