A new paper-based platform technology for point-of-care diagnostics

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Microfluidics

Background:

• Lateral flow immunoassays (LFIA) are limited in performing complex multi-step tests due to challenges in autonomous, controlled reagent introduction.
• Existing LFIA technologies lack the capability for sequential and timed delivery of multiple reagents to the detection zone.

Purpose of the Study:

• To develop a novel point-of-care (POC) paper-based lateral flow immunosensor.
• To incorporate microfluidic valve technology for autonomous control of fluidic networks and reagent delivery.
• To enable complex, multi-step immunoassays on a single, integrated device.

Main Methods:

• A three-dimensional paper and tape structure was fabricated to create a microfluidic network.
• Novel directional microfluidic valves were embedded within the test strip layers.
• A four-valve device was designed to autonomously direct sequential fluid flow for sample and reagent mixing.
• A three-step alkaline phosphatase-based Enzyme-Linked ImmunoSorbent Assay (ELISA) using Rabbit IgG was performed as a proof of concept.

Main Results:

• The developed device successfully controlled the sequential flow of three different fluids over the detection area.
• The immunosensor demonstrated suitability for complex immunoassays, as shown by the successful execution of a multi-step ELISA protocol.
• A sensitive detection limit of approximately 4.8 femtomolar (fm) was achieved for Rabbit IgG.

Conclusions:

• The novel microfluidic valve technology integrated into a paper-based lateral flow immunosensor enables autonomous, controlled multi-step immunoassays.
• This innovation overcomes limitations of traditional LFIA, paving the way for more sophisticated POC diagnostic tools.
• The device shows significant potential for sensitive and complex diagnostic testing in resource-limited settings.