Transverse solute dispersion in microfluidic paper-based analytical devices (μPADs)

URTEAGA, RAÚL; ELIZALDE, EMANUEL; BERLI, CLAUDIO L.A.

ANALYST

ROYAL SOC CHEMISTRY

Año: 2018

0003-2654

The transport of molecules and particles across adjacent flow streams is a key process in several operations implemented in microfluidic paper-based analytical devices (μPADs). Here, the transverse dispersion of a analytes was quantitatively evaluated by theory and experiments. Different tests were carried out to independently measure the coefficients of both Brownian diffusion and mechanical dispersion under capillary-driven flow. The dispersion width was found to be independent of fluid velocity and analyte properties, and fully determined by the dispersivity coefficient, which is a characteristic of the paper microstructure. This information introduces a change of paradigm for the design of mixers, diluters, and concentration gradient generators on μPADs; therefore, efforts were addressed to rationalize these operations on paper. The research reveals that mixers and concentration gradient generators can be much more efficient than their counterparts made on conventional microchannels; in contrast, separators such as the H-filter need to be appropriately engineered on paper, because the working principle can be hindered by mechanical dispersion. The knowledge gained throughout this work would contribute to design μPADs with a new level of precision and control over the formation of localized concentration profiles.