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Accueil > Publications > Archives 2004-2010 > 2009

Microfluidics with on-line dynamic light scattering for size measurements

F. Destremaut, J.-B. Salmon, L. Qi and J.-P. Chapel - Lab Chip 9, 3289 (2009)

publié le , mis à jour le

We present a detailed investigation on the feasibility of on-line dynamic light scattering measurements
of colloidal sizes in a pressure-driven microfluidic flow. We review some theoretical arguments
showing that such experiments are difficult to perform due to the Poiseuille flow that induces
interferences of different Doppler shifts. Such a theoretical approach is however very useful to figure
out the range of parameters where on-line size measurements are possible. We then build a dynamic
light scattering setup around a microfluidic chip that enables us to estimate the size of Brownian
scatterers flowing in PDMS-based microchannels, thus validating experimentally the theoretical
estimations. We finally present a microfluidic chip that can mix two reactants in around 200 ms, and allows
size measurements using dynamic light scattering at about 300 ms after complete mixing. Two
applications are presented : the continuous monitoring of the viscosity of a two-fluid mixture, and the
electrostatic co-assembly of oppositely charged nanoparticles and block copolymers.

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