Real-time droplet caliper for digital microfluidics

We developed an optical, microfabrication-free approach for performing real-time measurements of individual droplet characteristics (frequency of production, velocity, and length) flowing in a transparent microfluidic channel. Our approach consists in an interpretation of the differential signal pro...

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Bibliographic Details
Published in:Microfluidics and nanofluidics 2012-09, Vol.13 (2), p.261-271
Main Authors: Robert de Saint Vincent, Matthieu, Cassagnère, Sébastien, Plantard, Joël, Delville, Jean-Pierre
Format: Article
Language:English
Subjects:
Accessibility
Analytical Chemistry
Applied fluid mechanics
Biomedical Engineering and Bioengineering
Droplets
Engineering
Engineering Fluid Dynamics
Exact sciences and technology
Fluid Dynamics
Fluidics
Fundamental areas of phenomenology (including applications)
Instrumentation for fluid dynamics
Microfluidics
Nanocomposites
Nanomaterials
Nanostructure
Nanotechnology and Microengineering
Physics
Real time
Research Paper
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Summary:We developed an optical, microfabrication-free approach for performing real-time measurements of individual droplet characteristics (frequency of production, velocity, and length) flowing in a transparent microfluidic channel. Our approach consists in an interpretation of the differential signal produced by a pair of photodiodes connected head-to-tail due to the variations of illumination at the passage of a droplet. We checked the relevance of this zero-background method by comparing results to video measurements, and observed a very good agreement at rates up to the kHz range. Moreover, since the measured values are stored in a simple text file, flow characterization over very long times (several hours) becomes accessible. We applied this facility to perform three examples of long-term studies: stationary regimes, transient regimes, and the effect of an external forcing. Several unexpected features, like long-period fluctuations, can thus be evidenced.
ISSN:1613-4982
1613-4990
DOI:10.1007/s10404-012-0955-1