Magnetic timing valves for fluid control in paper-based microfluidics

Area of Science:

• Microfluidics
• Biomedical Engineering
• Analytical Chemistry

Background:

• Multi-step analytical tests, including enzyme-linked immunosorbent assays (ELISA), necessitate precise fluid delivery and timed incubation periods.
• Current paper-based microfluidic platforms often lack integrated, user-friendly fluid control mechanisms for temporal regulation.

Purpose of the Study:

• To develop and demonstrate a novel paper-based magnetic valve system capable of timed fluid control for microfluidic applications.
• To integrate timing capabilities into paper-based microfluidics for automated assay performance.

Main Methods:

• A paper timing channel with an ionic resistor was designed to detect fluid flow and trigger an electromagnet.
• The electromagnet actuates a paper cantilever valve, enabling normally-open or normally-closed configurations.
• Valve timing periods up to 30.3 ± 2.1 minutes were achieved and validated.

Main Results:

• Successfully developed paper-based magnetic valves with integrated timing functionality.
• Demonstrated timed fluid control, achieving reliable operation for periods relevant to assays like ELISA.
• Successfully performed an enzyme-based colorimetric reaction using the normally-open valve, showcasing its utility in timed substrate delivery.

Conclusions:

• The novel paper-based magnetic valves provide a new, user-friendly fluid control component for paper-based microfluidic devices.
• This technology has the potential to significantly enhance the automation and performance of complex assays on paper platforms.
• The developed valves offer a robust solution for timed fluidic operations, crucial for assays such as ELISA.