Numerical prototyping of paper-based gradient generators

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

Rio de Janeiro

Workshop; VIII Workshop in Microfluidics | I Brazil-Argentina Microfluidics Congress; 2018

The generation of concentration gradients is an essential operation for several analytical processes implemented on microfluidic paper-based analytical devices. The dynamic gradient formation is based on the transverse dispersion of chemical species across co-flowing streams. In paper channels, this transverse flux of molecules is dominated by mechanical dispersion, that is substantially different from molecular diffusion, which is the mechanism acting in conventional microchannels. Therefore, the design of gradient generators on paper requires new strategies. This work considers the foundations of transverse dispersion in porous substrates to investigate the optimal design of microfluidic paper-based concentration gradient generators by computer simulations. Virtual experiments were run to explore the ranges of operation and the overall performance of some devices. The physical prototypes were then fabricated and tested to prove the concepts.