Multifluidic device and processing system for colorimetric multiplexed detection of a substance

A microfluidic paper-based analytical device (μPAD) comprising:

• a paper-based substrate
• a non-polar material printed on a surface of the substrate such that a portion the surface is exposed, the exposed portion comprising a receiving area, a plurality of test areas, and a plurality of channels disposed between the receiving area and the test areas;
• and
• a plurality of colorimetric sensors respectively positioned in the test areas, the colorimetric sensors having respective aptamers requiring different saturation times before they are ready for analysis, wherein the channels are configured to receive an analyte solution from the receiving area and direct the analyte solution to the colorimetric sensors,
• wherein the receiving area is centrally positioned on the substrate and all of the test areas on the substrate are equidistant from the central receiving area to provide a consistent location for analysis of the test areas,
• wherein the widths of each of the channels are not the same and are sized to control a flow velocity of the analyte solution to each test area, such that the analyte solution arrives at each of the respective aptamers at times coordinated with the required saturation time of that aptamer, thereby ensuring that all test areas, despite having the aptamers requiring the different saturation times, reach readiness for analysis simultaneously.