480613 Demonstration of an Alginate Valve in a Paper Microfluidic Device

Monday, November 14, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
David Cornwell, BioEngineering, Mr., Corvallis, OR and Elain Fu, Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR

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, and have the potential to enable analytical field measurements for applications in healthcare, pharmaceuticals, environmental monitoring, and veterinary medicine. 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 is 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 Mylar 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. The valve has a response time dependent on calcium ion concentration. Currently 0.4 molar calcium chloride solution is able to close the valve within ~5 seconds, the approximate time taken to enter the central cellulose strip. The rate of fluid flow in the valve is lower than that of an alginate-free control. Fluid is typically able to reach the absorption pad in one minute, a 30 second increase over the standard flow time for fluid through a control cellulose strip without alginate. Current work focuses on characterizing the valveā€™s performance and demonstrating a reversible valve using a chelating agent such as EDTA.

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