Sommaire:

Abstract:

Although water is one of the most widespread material on the earth's surface and the most directly involved in a large number of phenomena, both natural and man-made; and although its molecule is made up of just 3 atoms, it still conceals many mysteries. Not all its physical and chemical properties are yet fully understood, especially when it is confined to nanometric spaces. It is therefore still the subject of in-depth fundamental studies. However, the many technical difficulties encountered when working at the nanometric scale mean that today, most published studies are theoretical rather than experimental. The need to collect experimental data is therefore essential, particularly from systems constituted of individual nano-objects. This is the general framework for the experimental research reported in this thesis. The work carried out can be divided into two distinct parts, each of which aims to contribute to the current and future experimental studies which will be carried out on water confined in a single nanopore.

The first part of the project involves the development of an experimental protocol for fabricating micro-platforms that are impervious to liquid water, water vapor and vacuum. The fabrication of these microsystems is based on micro photolithography techniques and the use of SU-8 resin. We show that it is possible to produce waterproof and vacuum-tight microsystems with SU-8 walls no thicker than 35 µm. The proposed protocol is therefore perfectly suited to the realization of Lab-on-Chip/nanofluidic micro-platforms dedicated to the study of water confined in a nanopore and to water nanofluidic.

The second part reports on a study of the impact of water on the electron transport of µ-field-effect transistors made of an individual single-walled carbon nanotube (SWCNT-FET). Microelectronics techniques to design and manufacture a µ-platform consisting of several microelectrodes in contact with a single nanotube are used. These electrodes made it possible either to carry out electrical measurements or to use the Joule effect to open the nanotube at specific points and also to heat it to temperatures high enough to eliminate all traces of water from its environment. The electron transport response of the SWCNT-FET as a function of the environment around the nanotube, i.e. liquid water, ambient air, and vacuum is analyzed. A comparison is made between the responses obtained when the nanotube is closed or open. It is thus possible to propose a simplified qualitative model of interaction with water and to distinguish the impact created by water adsorbed outside the tube from that associated with water confined within the tube. This pioneering work opens up many new prospects on water in the fields of nanofluidic and fundamental studies about its structure and the dynamics of its molecules in a confined environment. First and foremost, it will be used to develop a µ-measurement platform based on the electromechanical characteristics of a single carbon nanotube in the presence of water either solid, liquid or vapour.

Pour plus d'informations, merci de contacter Metz R.