Design keys for paper-based concentration gradient generators

SCHAUMBURG, FEDERICO; URTEAGA, RAÚL; KLER, PABLO A.; BERLI, CLAUDIO L.A.

JOURNAL OF CHROMATOGRAPHY - A

ELSEVIER SCIENCE BV

Año: 2018

0021-9673

tThe generation of concentration gradients is an essential operation for several analytical processes imple-mented on microfluidic paper-based analytical devices. The dynamic gradient formation is based on thetransverse dispersion of chemical species across co-flowing streams. In paper channels, this transverse flux of molecules is dominated by mechanical dispersion, which is substantially different than molecular diffusion, which is the mechanism acting in conventional microchannels. Therefore, the design of gradient generators on paper requires strategies different from those used in traditional microfluidics. This work considers the foundations of transverse dispersion in porous substrates to investigate the optimal designof microfluidic paper-based concentration gradient generators (mPGGs) by computer simulations. A setof novel and versatile mPGGs were designed in the format of numerical prototypes, and virtual exper-iments were run to explore the ranges of operation and the overall performance of such devices. Thenphysical prototypes were fabricated and experimentally tested in our lab. Finally, some basic rules forthe design of optimized mPGGs are proposed. Apart from improving the efficiency of mixers, diluters and mPGGs, the results of this investigation are relevant to attain highly controlled concentration fields onpaper-based devices.