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Dissolvable fluidic time delays for programming multi-step assays in instrument-free paper diagnostics
Barry Lutz1, Tinny Liang, Elain Fu
1University of Washington, Department of Bioengineering, 3720 15th Ave NE, Box 355061, Seattle, WA 98195, USA. blutz@uw.edu
Lab on a Chip
|May 21, 2013
Summary
Researchers developed programmable paper-based fluidic devices using dissolvable sugar to automate multi-step diagnostic assays. This innovation enables complex laboratory protocols in a simple, rapid, and low-cost format for point-of-care testing.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Materials Science
Background:
- Lateral flow tests (LFTs) offer rapid diagnostics but are limited to single-step chemistries.
- Laboratory diagnostic assays typically require multiple timed steps, often needing specialized equipment or trained personnel.
- There is a need for accessible, low-cost diagnostic platforms capable of performing complex, multi-step assays outside of laboratory settings.
Purpose of the Study:
- To develop a novel paper-based fluidic system capable of automating multi-step diagnostic protocols.
- To utilize programmable fluidic delays through dissolvable sugar matrices to control assay timing.
- To demonstrate the feasibility of this system for a signal-amplified immunoassay in a point-of-care format.
Main Methods:
- Paper strips were treated with varying concentrations of sucrose (10-70% saturation) and dried to create programmable fluidic time delays.
- A paper network topology was designed to orchestrate sequential fluidic steps.
- A folding card format was engineered for single-step user activation, initiating a multi-step automated assay.
- The device was validated using a signal-amplified sandwich immunoassay for a malaria biomarker.
Main Results:
- Sucrose-based delays successfully controlled fluid flow for durations ranging from minutes to nearly an hour.
- A simple folding card format automated a four-step fluidic process initiated by a single user action.
- The developed device successfully performed a signal-amplified sandwich immunoassay, demonstrating its diagnostic potential.
- The system proved capable of automating complex laboratory-based assay protocols.
Conclusions:
- Dissolvable sugar-based delays integrated into paper networks enable programmable, automated multi-step fluidic protocols.
- This technology offers a pathway to translate complex laboratory diagnostic assays into rapid, low-cost, and user-friendly point-of-care devices.
- The developed platform holds significant potential for improving infectious disease diagnostics, such as for malaria, in resource-limited settings.
