Étude, conception et caractérisation de structures « MEMS » résonantes non linéaires pour la récupération d’énergie vibratoire et la génération d’ultrasons

Abstract

Today’s world is connected, tomorrow’s will be even more so. These connections are provided by connected objects that surround us, collecting and communicating data whose volume is constantly increasing. It is the advent of the Internet of Things (IoT) which helps and motivates the development of new types of micro-electromechanical systems (MEMS) in order to fulfill the functions of sensors but also to supply energy to these sensor networks. This work aims to contribute to the advancement of knowledge accumulated in the field of (MEMS), in particular this work focuses on resonant MEMS dedicated to the recovery of vibratory energy and the generation of ultrasound. To do this, first, a literature review is presented. It focuses on the MEMS devices, their fabrication and their applications. Following this literature review, the design, fabrication and characterization of "Squared daisy" type structures is presented . The main advantages of this structure are the presence of multiple resonance modes, is resistance to manufacturing process variations and its a non-linear frequency response. The influence of the anchoring in "squared daisy" structures on the type of non-linearity is then presented. This includes a method of characterization of the performances of the non-linear MEMS resonators which makes it possible to mitigate hysteresis. A method of non-linear MEMS excitation which has been named "pulse shaping" is then proposed. This method uses the properties of non-linear micromachined ultrasonic transducers (MUT) to improve their performance. It should be noted that this method has many advantages : it allows for the increase of the displacement of the membrane, the control the operating frequency and the reduction of the decay time of the MUT. Ultimately, this thesis describes the study, design and characterization of a nonlinear resonant MEMS structure for energy harvesting from vibrations. These devices were then used to develop a characterization method for non-linear resonators, and to elaborate a technique to improve the generation of ultrasound. These methods will undoubtedly allow the development of new applications and will thus contribute to the advancement of scientific knowledge on resonant MEMS.

Date	11 Apr 2022
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Frédéric Nabki (Supervisor)