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Issue 14, 2013
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Dissolvable fluidic time delays for programming multi-step assays in instrument-free paper diagnostics

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Abstract

Lateral flow tests (LFTs) are an ingenious format for rapid and easy-to-use diagnostics, but they are fundamentally limited to assay chemistries that can be reduced to a single chemical step. In contrast, most laboratory diagnostic assays rely on multiple timed steps carried out by a human or a machine. Here, we use dissolvable sugar applied to paper to create programmable flow delays and present a paper network topology that uses these time delays to program automated multi-step fluidic protocols. Solutions of sucrose at different concentrations (10–70% of saturation) were added to paper strips and dried to create fluidic time delays spanning minutes to nearly an hour. A simple folding card format employing sugar delays was shown to automate a four-step fluidic process initiated by a single user activation step (folding the card); this device was used to perform a signal-amplified sandwich immunoassay for a diagnostic biomarker for malaria. The cards are capable of automating multi-step assay protocols normally used in laboratories, but in a rapid, low-cost, and easy-to-use format.

Graphical abstract: Dissolvable fluidic time delays for programming multi-step assays in instrument-free paper diagnostics

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Supplementary files

Article information


Submitted
07 Feb 2013
Accepted
07 May 2013
First published
10 May 2013

Lab Chip, 2013,13, 2840-2847
Article type
Paper

Dissolvable fluidic time delays for programming multi-step assays in instrument-free paper diagnostics

B. Lutz, T. Liang, E. Fu, S. Ramachandran, P. Kauffman and P. Yager, Lab Chip, 2013, 13, 2840
DOI: 10.1039/C3LC50178G

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