Higher beating degrees reduced the flow rates, possibly due to a decrease in pore size. Calendering had a minimal effect on the flow rates. Based on these findings, it was shown that printing PS-co-PAA ink using an inkjet printer is a feasible way to fabricate hydrophobic barriers of channels for aqueous liquid delivery in paper substrates. This technique is expected to contribute to the creation of paper-based sensors simply and efficiently at low costs. Furthermore, channels fabricated on paper substrates prepared from less beaten pulp and along the machine direction, regardless of calendering degrees, are considered advantageous for a higher longitudinal flow rate to save time in μPADs sensing tests. From a paper science perspective, the conclusions drawn from this research are universal for paper without special treatment. Overall, this study provides valuable insights into the design and optimization of μPADs for rapid and low-cost sensing applications.