Thesis defense by Morgane BONNEL

New generation of optical chemical sensors: study of a microstructured architecture fluorescent channel waveguide / diffraction gratings developed by sol-gel route


Keywords:

Channel waveguide – Diffraction gratings – Sol-gel – Dissolved oxygen – Photolithography – Fluorescence







cliquer pour voir la liste des membres du jury/clic here for the jury members
 

Abstract

A flagship application of miniaturized chemical optical sensors is the real-time monitoring of cell cultures in the biomedical field. The principle of these sensors is based on variations of the fluorescence signal when a fluorophore, encapsulated in a matrix permeable to gaseous or ionic species and excited to a suitable wavelength, is contacted with an analyte, e.g. dissolved oxygen (DO) in an aqueous medium. Their integration in the form of miniaturized devices is based on the deposition of a thin-layer matrix doped with the fluorophore. While this configuration is perfectly suited to miniaturized devices, it suffers from limitations in terms of detection limit due to the small amount of fluorophores incorporated in the thin-film matrix and to the small fraction of light emitted redirected toward the photodetector. The thesis aims at proposing a new sensor configuration based on the sol-gel fabrication of fluorophore-doped channel waveguides equipped with diffracting couplers. This work particularly highlights the potential of a high refractive index titanium oxide based sol-gel photoresist that can be imprinted through a single photolithography step (selective insolation / development) to form a given pattern. We firstly present the elaboration process of the micro-structured architecture composed of diffraction gratings imprinted on channel waveguides. Both components of this architecture have been optimized based on opto-geometrical characterizations and modeling. The efficiency of light coupling in the channel waveguide using diffraction gratings is then presented and discussed, as well as studies showing the possibility to collect a fluorescence signal propagating in the waveguide. Finally, the integration of the device into a microfluidic system made it possible to carry out first fluorescence measurements according to a procedure appropriate to the intended application, i.e. to be able in fine to measure variable DO levels in different fluids via fluorescence measurements in guided configuration.

Membres du jury/ Jury members :
 

Prof.

S.Callard

INL, Ecole Centrale de Lyon, Lyon (France)

Examinatrice / Présidente du jury

Prof.

G.Chadeyron

ICCF, Ecole SIGMA Clermont, Aubière (France)

Rapporteuse

DR.

O.Soppera

IS2M, CNRS, Mulhouse (France)

Rapporteur

Talent Manager

E.Meurville

EPFL, VP RHO, Lausanne (Suisse)

Examinateur

MC

A.Morand

IMEP-LAHC, Université Grenoble Alpes, Grenoble (France)

Examinateur

DR.

M.Langlet

LMGP, CNRS, Grenoble (France)

Directeur de thèse

MC

D.Riassetto

LMGP, Grenoble INP, Grenoble (France)

Co-encadrant de thèse




 

Date infos
2:30 pm - Z 108 - Phelma Bâtiment Z
Location infos
Grenoble INP - Phelma
3 parvis Louis Néel - 38000 Grenoble
Accès : TRAM B arrêt Cité internationale
Free entrance - No registration