A Compact Device for Urine Collection and Transport in Porous Media

摘要

We investigate capillary flow in filter paper in compact point-of-care microfluidic devices for transport of liquid samples to sensing pads. Particular challenges were the effects of gravity, unintended capillaries, contamination and evaporation, and the purpose is to investigate solutions to achieve a robust device. On the condition that the liquid sample has sufficient time to saturate the filter paper, the transport of miscible liquid contaminants are mainly left to the mechanisms of diffusion, which was found to provide an inherent resistance to contamination. However, unintended capillaries between the filter paper and a surface provided an increase in the transport rate for both sample and contamination. This was avoided by sealing possible gaps on the sides of the filter paper with adhesive tape, and by applying a force perpendicular to the paper surface to flatten paper and prevent formation of air pockets between the filter paper surface and contacting surfaces.