Capillary flow control in lateral flow assays via delaminating timers

Area of Science:

• Biotechnology
• Analytical Chemistry
• Materials Science

Background:

• Lateral flow assays (LFAs) offer simple, point-of-care analyte detection but are limited by uncontrolled capillary flow, hindering complex, multi-step reactions.
• Conventional LFAs struggle with sequential reagent delivery, restricting their application in sophisticated biochemical analyses.

Purpose of the Study:

• To develop a novel technique for precisely controlling capillary flow in paper-based devices.
• To enable timed, sequential introduction of multiple reagents for complex chemical reactions on paper.
• To enhance the sensitivity of LFAs and create portable devices for biological sample processing.

Main Methods:

• A technique was developed to control capillary flow by imprinting water-insoluble ink roadblocks on the flow path.
• Timers were created using the gradual formation of a void between wetted paper and a sheath polymer tape to regulate flow duration.
• The technique was applied to develop a sensitive LFA for human chorionic gonadotropin detection and a DNA extraction device.

Main Results:

• The developed technique successfully controlled capillary flow, enabling programmed sequential liquid delivery.
• A novel LFA demonstrated an order of magnitude increase in sensitivity for human chorionic gonadotropin detection due to built-in signal amplification.
• A portable device for DNA extraction from bodily fluids was successfully created, eliminating the need for laboratory instruments.

Conclusions:

• This new method overcomes the limitations of capillary flow in paper-based devices, enabling complex, timed reactions.
• The technique significantly enhances LFA sensitivity and facilitates the development of instrument-free diagnostic and sample preparation tools.
• This approach holds promise for advancing point-of-care diagnostics and field-based biological sample analysis.