Microfluidic in-line dynamic light scattering with a commercial fibre optic system

We report the coupling of dynamic light scattering (DLS) in microfluidics, using a contact-free fibre-optic system, enabling the under-flow characterisation of a range of solutions, dispersions, and structured fluids. The system is evaluated and validated with model systems, specifically micellar an...

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Bibliographic Details
Published in:Lab on a chip 2023-05, Vol.23 (11), p.254-2552
Main Authors: Torquato, Luis M. G, Hélaine, Nelson, Cui, Yufan, O'Connell, Roisin, Gummel, Jérémie, Robles, Eric S. J, Jacob, David, Cabral, João T
Format: Article
Language:English
Subjects:
Chemical Sciences
Continuous flow
Data points
Dispersions
Fiber optics
Flow measurement
Flow velocity
Microfluidics
Photon correlation spectroscopy
Saline solutions
Scattering
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Summary:We report the coupling of dynamic light scattering (DLS) in microfluidics, using a contact-free fibre-optic system, enabling the under-flow characterisation of a range of solutions, dispersions, and structured fluids. The system is evaluated and validated with model systems, specifically micellar and (dilute) polymer solutions, and colloidal dispersions of different radii (∼1-100 nm). A systematic method of flow-DLS analysis is examined as a function of flow velocity (0-16 cm s −1 ), and considerations of the relative contribution of 'transit' and 'Brownian' terms enable the identification of regions where (i) a quiescent approximation suffices, (ii) the flow-DLS framework holds, as well as (iii) where deviations are found, until eventually (iv) the convection dominates. We investigate practically relevant, robust setups, namely that of a capillary connected to microdevice, as well as direct measurement on a glass microdevice, examining the role of capillary dimensions and challenges of optical alignment. We conclude with a demonstration of a continuous flow measurement of a binary surfactant/salt solution, whose micellar dimensions vary with composition, characterised with hundreds of data points (every ∼5 s) and adequate statistics, within a few minutes. We report the coupling of dynamic light scattering (DLS) in microfluidics, using a contact-free fibre-optic system, enabling the under-flow characterisation of a range of solutions, dispersions, and structured fluids.
ISSN:1473-0197
1473-0189
DOI:10.1039/d3lc00062a