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Proceedings Paper

Fluorescence cross-correlation spectroscopy for time dependent flows: a numerical investigation
Author(s): Nicolo' Giovanni Ceffa; Paolo Pozzi; Margaux Bouzin; Cassia Alessandra Marquezin; Laura Sironi; Laura D'Alfonso; Maddalena Collini; Giuseppe Chirico
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Paper Abstract

We have previously addressed experimentally blood fluidodynamics in microcapillaries by coupling optical microscopy to pixelated detection. By computing the Cross-Correlation Function (CCF) of signals coming from pixels at a distance along the flow we obtained information on the flow speed and direction. The extension of these experiments to more complex systems with high branching of capillaries and/or inverted flows needs a theoretical investigation that we present here. We focus first on straight capillaries and harmonic flows between a minimum Vmin ≠ 0 and a maximum Vmax flow speed. The CCF shows multiple peaks at lag times that correspond closely to the maximum and minimum flow speeds. The general analytical expression of the CCF is given, the position of its maxima are discussed by means of geometrical considerations and numerical analysis and an experimental validation are presented. The second case that we study is the flow in the branches of a y-shaped junction in a microcapillary. By simply modeling the branching in laminar flow (low Reynold numbers) and assuming a smooth transition of speeds along the branches we derive a simple numerical model to compute the trajectories of micro-beads. We estimate the flow speed in the branches by computing the CCFs between linear regions of interest set perpendicular to the axes of the branches.

Paper Details

Date Published: 5 March 2015
PDF: 13 pages
Proc. SPIE 9320, Microfluidics, BioMEMS, and Medical Microsystems XIII, 93200R (5 March 2015); doi: 10.1117/12.2077088
Show Author Affiliations
Nicolo' Giovanni Ceffa, Univ. degli Studi di Milano-Bicocca (Italy)
Paolo Pozzi, Univ. degli Studi di Milano-Bicocca (Italy)
Margaux Bouzin, Univ. degli Studi di Milano Bicocca (Italy)
Cassia Alessandra Marquezin, Univ. degli Studi di Milano Bicocca (Italy)
Univ. Federal de Goiás (Brazil)
Laura Sironi, Univ. degli Studi di Milano-Bicocca (Italy)
Laura D'Alfonso, Univ. degli Studi di Milano-Bicocca (Italy)
Maddalena Collini, Univ. degli Studi di Milano-Bicocca (Italy)
Giuseppe Chirico, Univ. degli Studi di Milano-Bicocca (Italy)

Published in SPIE Proceedings Vol. 9320:
Microfluidics, BioMEMS, and Medical Microsystems XIII
Bonnie L. Gray; Holger Becker, Editor(s)

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