- Paper microfluidic devices are capable of processing fluids using capillary flow in materials that are lower cost than the standard materials used in microfluidics. Due to the low cost of their fabrication and minimal requirements for instrumentation, paper microfluidic devices are ideal for use in low-resource settings. They have the potential to enable analytical field measurements for applications in healthcare, pharmaceuticals, and environmental monitoring. The precise control of fluid flow in paper microfluidic devices is critical to achieving the effectiveness and reliability of more conventional alternatives and to reaching the full potential of paper microfluidics. The goal of this research project was to create an alginate-based hydrogel valve that can stop the flow of fluid in a paper microfluidic channel when sodium alginate is converted to calcium alginate, forming a cross-linked hydrogel. The novel valve is demonstrated in a lateral flow device. The main channel is composed of alginate-filled cellulose and two nitrocellulose connector strips, a glass fiber source pad, and a cellulose wicking pad, all of which are mounted on a polyester backing. Initially, the valve is in the open state and allows fluid flow. Upon the addition of calcium ions, the alginate forms the cross-linked hydrogel, which blocks fluid flow.
Key Words: Paper Microfluidics, Alginate, Microfluidics, Valve, Hydrogel, Lateral