arXiv subjects

Florence Gibouin

Publications and source records attributed to Florence Gibouin.

3 recordsLinked to original sources

arXiv2025

Fluorescent molecular rotor-based polymer materials for local microviscosity mapping in microfluidic channels

A viscosity-sensitive monomer consisting of a methacrylate-functionalized julolidone-based molecular rotor (MECVJ) was synthesized and used to obtain viscosity-sensitive polymers (poly(DMA-\textit{s}-MECVJ)). The qualitative properties of the molecular rotor were preserved after its inclusion in the new polymer, in particular the effect of the viscosity of the surrounding medium on the fluorescence lifetime of the rotor. By grafting these polymers onto glass slides, viscosity-sensitive surfaces were obtained, showing good robustness in time after successive use and washing. As proof of concept, these surfaces were used to assemble a microfluidic chip capable of mapping viscosity of fluids flowing inside the channel.

cond-mat.soft↗

arXiv2024

Molecular rotors for in situ local viscosity mapping in microfluidic chips

In numerous industrial processes involving fluids, viscosity is a determinant factor for reaction rates, flows, drying, mixing, etc. Its importance is even more determinant for phenomena observed are at the micro- and nano- scales as in nanopores or in micro and nanochannels for instance. However, despite notable progresses of the techniques used in microrheology in recent years, the quantification, mapping and study of viscosity at small scales remains challenging. Fluorescent molecular rotors are molecules whose fluorescence properties are sensitive to local viscosity: they thus allow to obtain viscosity maps by using fluorescence microscopes. While they are well-known as contrast agents in bioimaging, their use for quantitative measurements remains scarce. This paper is devoted to the use of such molecules to perform quantitative, \textit{in situ} and local measurements of viscosity in heterogeneous microfluidic flows. The technique is first validated in the well-controlled situation of a microfluidic co-flow, where two streams mix through transverse diffusion. Then, a more complex situation of mixing in passive micromixers is considered and mixing efficiency is characterized and quantified. The methodology developed in this study thus opens a new path for flow characterization in confined, heterogeneous and complex systems.he methodology developed in this study thus opens a new path for flow characterization in confined, heterogeneous micro- and nano- systems.

physics.flu-dyn↗

arXiv2024

Molecular Rotors for In Situ Viscosity Mapping during Evaporation of Confined Fluid Mixtures

Numerous formulation processes of materials involve a drying step, during which evaporation of a solvent from a multi-component liquid mixture, often confined in a thin film or in a droplet, lead to concentration and assembly of non volatile compounds. While the basic phenomena ruling evaporation dynamics are known, a precise modeling of practical situations is hindered by the lack of tools for local and time-resolved mapping of concentration fields in such confined systems. In this article, the use of Fluorescence Lifetime Imaging Microscopy and of Fluorescent Molecular Rotors is introduced as a versatile, in-situ and quantitative method to map viscosity and concentration fields in confined, evaporating liquids. More precisely, the cases of drying of a suspended liquid film and of a sessile droplet of mixtures of fructose and water is investigated. Measured viscosity and concentration fields allow to characterize drying dynamics, in agreement with simple modeling of the evaporation process.

cond-mat.soft↗