Semi-quantitative Lateral Flow Assay Using a Handheld Device with a Transmissive Readout

Daniel Nguyen; Iida Jaaskelainen; Duc Le; Anu Mursula; Sanna Aikio; Christina Liedert; Jussi Hiltunen

doi:10.1109/JSEN.2025.3618661

Semi-quantitative Lateral Flow Assay Using a Handheld Device with a Transmissive Readout

Daniel Nguyen^*
, Iida Jaaskelainen
, Duc Le
, Anu Mursula
, Sanna Aikio
, Christina Liedert
, Jussi Hiltunen

^*Corresponding author for this work

Research output: Contribution to journal › Article › Scientific › peer-review

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Abstract

Lateral flow assays (LFAs) are widely used for rapid and cost-effective diagnostic testing. The assays are often qualitative relying on a binary interpretation of the results on test strips. In many applications, however, quantitative or semi-quantitative readout is needed to define the analyte molecule concentration in a sample matrix, such as, saliva or urine. This study focuses on developing a semi-quantitative LFA test concept with a customized test strip cartridge and transmissive optical detection. LFA was developed to detect Covid-19 proteins and the coloration of the test line was induced by the concentration of plasmonic nanoparticles. Spectroscopic characterization of the test strips showed that the signal strength was enhanced by 82% on average when the conventional reflection-based detection was substituted by a transmission detection. When a set of LFA tests were read with the developed handheld optoelectronic device, the observed standard deviation was found to be below 3% meeting the requirements for semi-quantitative analyses.

Original language	English
Pages (from-to)	1915-1922
Number of pages	8
Journal	IEEE Sensors Journal
Volume	26
Issue number	2
DOIs	https://doi.org/10.1109/JSEN.2025.3618661
Publication status	Published - 2026
MoE publication type	A1 Journal article-refereed

Funding

This work was supported in part by the Research Council of Finland grants Printed Intelligence Infrastructure with decision 358621 and Photonics Research and Innovation (PREIN) with decision 368651, and by the Business Finland grant Future of Diagnostics (FUDIS) with decision 37178/31/2020. All the authors are with VTT – Technical Research Centre of Finland (email: [email protected]).

Keywords

Lateral flow assay (LFA)
Rapid tests
Spectroscopy
Test strip reader

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JSEN.2025.3618661Final published version, 4.73 MBLicence: CC BY

Cite this

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title = "Semi-quantitative Lateral Flow Assay Using a Handheld Device with a Transmissive Readout",

abstract = "Lateral flow assays (LFAs) are widely used for rapid and cost-effective diagnostic testing. The assays are often qualitative relying on a binary interpretation of the results on test strips. In many applications, however, quantitative or semi-quantitative readout is needed to define the analyte molecule concentration in a sample matrix, such as, saliva or urine. This study focuses on developing a semi-quantitative LFA test concept with a customized test strip cartridge and transmissive optical detection. LFA was developed to detect Covid-19 proteins and the coloration of the test line was induced by the concentration of plasmonic nanoparticles. Spectroscopic characterization of the test strips showed that the signal strength was enhanced by 82\% on average when the conventional reflection-based detection was substituted by a transmission detection. When a set of LFA tests were read with the developed handheld optoelectronic device, the observed standard deviation was found to be below 3\% meeting the requirements for semi-quantitative analyses.",

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author = "Daniel Nguyen and Iida Jaaskelainen and Duc Le and Anu Mursula and Sanna Aikio and Christina Liedert and Jussi Hiltunen",

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AU - Nguyen, Daniel

AU - Jaaskelainen, Iida

AU - Le, Duc

AU - Mursula, Anu

AU - Aikio, Sanna

AU - Liedert, Christina

AU - Hiltunen, Jussi

PY - 2026

Y1 - 2026

N2 - Lateral flow assays (LFAs) are widely used for rapid and cost-effective diagnostic testing. The assays are often qualitative relying on a binary interpretation of the results on test strips. In many applications, however, quantitative or semi-quantitative readout is needed to define the analyte molecule concentration in a sample matrix, such as, saliva or urine. This study focuses on developing a semi-quantitative LFA test concept with a customized test strip cartridge and transmissive optical detection. LFA was developed to detect Covid-19 proteins and the coloration of the test line was induced by the concentration of plasmonic nanoparticles. Spectroscopic characterization of the test strips showed that the signal strength was enhanced by 82% on average when the conventional reflection-based detection was substituted by a transmission detection. When a set of LFA tests were read with the developed handheld optoelectronic device, the observed standard deviation was found to be below 3% meeting the requirements for semi-quantitative analyses.

AB - Lateral flow assays (LFAs) are widely used for rapid and cost-effective diagnostic testing. The assays are often qualitative relying on a binary interpretation of the results on test strips. In many applications, however, quantitative or semi-quantitative readout is needed to define the analyte molecule concentration in a sample matrix, such as, saliva or urine. This study focuses on developing a semi-quantitative LFA test concept with a customized test strip cartridge and transmissive optical detection. LFA was developed to detect Covid-19 proteins and the coloration of the test line was induced by the concentration of plasmonic nanoparticles. Spectroscopic characterization of the test strips showed that the signal strength was enhanced by 82% on average when the conventional reflection-based detection was substituted by a transmission detection. When a set of LFA tests were read with the developed handheld optoelectronic device, the observed standard deviation was found to be below 3% meeting the requirements for semi-quantitative analyses.

KW - Lateral flow assay (LFA)

KW - Rapid tests

KW - Spectroscopy

KW - Test strip reader

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Semi-quantitative Lateral Flow Assay Using a Handheld Device with a Transmissive Readout

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