Microfluidic Paper-based Analytical Devices, μPADs, utilize capillary action to transport reagents, eliminating the need for a pump, which makes the device small and inexpensive. However, there are challenges in fluid control and difficulties in using multiple reagents. To achieve fluid control on paper analysis chips, we developed valves by filling porous materials with thermo-responsive resin. The developed valves function by changing volume due to the hydrophilic-hydrophobic transition of the thermo-responsive polymer at 32°C. By integrating multiple such valves into the paper analysis chip, we achieved fluid control of multiple reagents. In addition, to demonstrate that protein analysis is possible with the developed μPAD, a colorimetric analysis of IgG was conducted. As a result, by incorporating multiple valves into the μPAD, it is possible to flow fluids in any desired order, and it was found that the developed μPAD can capture IgG and quantitatively measure its concentration.
KAI et al. (Wed,) studied this question.