The automatic fluidic flow control is achieved through the use of multiple SMPactuated valves. These paper valves are actuated using a thermally responsive, dual-state shape transformation of a SMP sheet attached to the root of a paper cantilever beam, which drives a hydrophilic paper bridge to connect and disconnect two paper channels. A portable colorimetric reader has been developed to control the on-chip valve operations, quantify the colorimetric signal output, display the assay result, and wirelessly transmit the data to a smartphone for the application of telemedicine. The platform has been demonstrated to be reliable, with success rates of 97% and 93% for the paper valve and the entire μPAD, respectively. A detection mechanism for valve malfunction has been designed and confirmed to be effective in identifying any mal-operation of individual valves, thus rendering the platform reliable in real assays. The platform has been calibrated using direct ELISAs of rabbit IgG in phosphate-buffered saline (PBS) and has achieved a low limit of In multi-step analytical assays, such as enzyme-linked immunosorbent assays (ELISAs), precise delivery of multiple fluids into a reaction zone and accurate timing of incubation at each step are crucial. In this regard, paper-based microfluidic devices have emerged as a promising alternative to traditional laboratory equipment due to their portability, low cost, and simplicity. However, one of the challenges in developing these devices is the lack of a reliable mechanism for controlling the timing of fluidic flow. To address this issue, a team of researchers has developed a novel type of paper-based magnetic valve that can count the time and turn on or off fluidic flow according to the incubation time required at each step. The timing capability of these valves is based on a paper timing channel with an ionic resistor that can detect the event of a solution flowing through the Another group of researchers have developed a hydrophobic wax barrier, also known as a "wax gate," combined with surfactants as a valving mechanism for paper-based microfluidic systems. This mechanism enables the control of delays in reagent addition in the device, making it possible to perform multistep analysis on μPADs. In this work, the researchers investigated three geometries of the wax gates, including line, arc, and triangle, and found that the triangle and arc gates performed significantly better than the line gate as hydrophobic barriers. Using the triangle wax gate, the actuation time of the wax gate could be controlled in the range of approximately 2-21 minutes, depending on the concentration of the surfactants. One of the advantages of this mechanism is its independence from delay channels and sample solution, which allows end-users to extend temporal control as needed. Furthermore, the researchers were able to easily integrate the triangle wax gate into a prototype multistep sandwich immunosensor, which allowed for the sensitive detection of mouse-IgG and SARS-CoV2 antibody. The development of this simple, compact, and independent flow control mechanism is a significant breakthrough in the field of paper-based microfluidics. By using a single piece of cellulose paper, the entire μPAD, including the wax gate mechanism, can be fabricated via one-step of wax-printing. The improved actuation time of the wax gate mechanism compared to previous designs, and the enhanced functionality provided by the triangle shape, make it a promising technology for applications requiring multiple steps of liquid manipulation on paper-based devices. These might include silver/gold enhancement, nanoparticle-catalyzed amplification, polymerization-based signal enhancement, and other enzyme-substrate reactions.