Thèse Théo Travers

Le 12 décembre 2022

Lundi 12 décembre à 14h00 à Angers (amphi L003), Théo Travers soutiendra sa thèse intitulée :

Caractérisation de nano-sources de lumière en régime microfluidique grâce à la microscopie non-linéaire.

Composition du Jury

• Dr. Martinus Werts (SATIE, ENS Rennes), rapporteur
• Pr. Jérôme Plain (L2n, Université de technologie de Troyes), rapporteur
• Pr. Guillaume Brotons (IMMM, Le Mans Université), examinateur
• Dr. Abdel Illah El Abed (LIMIN, Université Paris Saclay), examinateur
• Pr. Denis Gindre (MOLTECH-Anjou, Université d'Angers), directeur de thèse
• Dr. Matthieu Loumaigne (MOLTECH-Anjou, Université d'Angers), co-directeur de thèse

Abstract

Non-linear microscopy has allowed for several years to evolve the observation of biological tissues thanks to an improvement in contrast when the samples are dense and thick. Thanks to its excitation volume confinement which brings a better resolution and its non-destructive effect due to its less energetic wavelength, nonlinear microscopy has become widely used. Nevertheless, the generation of nonlinear effects imposes technical limitations such as scanning a laser beam to image the sample response. This can restrict the use of nonlinear microscopy to experiments where the emitters are static or at least where the overall signal evolves slowly relative to the rate of image acquisition. However, many experiments in biology require the monitoring of individual biomarkers grafted to molecules of interest for the understanding of interactions or transport phenomena within living cells. Most often this is done with single photon fluorescence microscopy which can cause phototoxicity problems due to the excitation wavelengths used. To overcome this, the aim of this thesis is to adapt the use of non-photototoxic non-linear microscopy, but limited in framerate by its scanning, to the individual follow-up of light nano-emitters agitated by a free diffusion movement. This study must answer this problem by establishing a compromise between the spatial resolution of the images giving access to the localization of the nano-emitters and the framerate allowing to obtain statistical estimations resulting from reliable trajectories. These two parameters of resolution and acquisition rate being closely linked, the determination of an included required to address the concepts of minimum sampling and statistical uncertainties. The objective of this work was also extended to the control of a new microfluidic chip manufacturing process. This allowed the development of a light sheet microscopy integrated to a microfluidic chip by means of two optical fibers very simple to set up. In order to apply the measurement tools and experimental supports, a first study on the formation of aggregates in microfluidic channels is presented using the flow-focusing and zero-flow methods which aim at forcing the aggregation of fluorescent molecules in order to estimate their size by stopping the flow and studying their diffusion motion.