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Issue 2, 2014
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Biosensor design based on Marangoni flow in an evaporating drop

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Effective point-of-care diagnostics require a biomarker detection strategy that is low-cost and simple-to-use while achieving a clinically relevant limit of detection. Here we report a biosensor that uses secondary flows arising from surface Marangoni stresses in an evaporating drop to concentrate target-mediated particle aggregates in a visually detectable spot. The spot size increases with increasing target concentration within the dynamic range of the assay. The particle deposition patterns are visually detectable and easily measured with simple optical techniques. We use optical coherence tomography to characterize the effect of cross-sectional flow fields on the motion of particles in the presence and absence of target (aggregated and non-aggregated particles, respectively). We show that choice of substrate material and the presence of salts and glycerol in solution promote the Marangoni-induced flows that are necessary to produce signal in the proposed design. These evaporation-driven flows generate signal in the assay on a PDMS substrate but not substrates with greater thermal conductivity like indium tin oxide-coated glass. In this proof-of-concept design we use the M13K07 bacteriophage as a model target and 1 μm-diameter particles surface functionalized with anti-M13 monoclonal antibodies. Using standard microscopy-based techniques to measure the final spot size, the assay has a calculated limit-of-detection of approximately 100 fM. Approximately 80% of the maximum signal is generated within 10 minutes of depositing a 1 μL drop of reacted sample on PDMS enabling a relatively quick time-to-result.

Graphical abstract: Biosensor design based on Marangoni flow in an evaporating drop

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Supplementary files

Article information

28 Aug 2013
07 Nov 2013
First published
08 Nov 2013

Lab Chip, 2014,14, 315-324
Article type

Biosensor design based on Marangoni flow in an evaporating drop

J. R. Trantum, M. L. Baglia, Z. E. Eagleton, R. L. Mernaugh and F. R. Haselton, Lab Chip, 2014, 14, 315
DOI: 10.1039/C3LC50991E

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