Public thesis defense Loïc LAHAYE - ICTEAM
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Flexible MEMS-based Platform for High-Strain Characterization of Silicon and Vanadium Dioxide Devices
Friday September 18th, 2026 - 4:15pm - Auditorium BARB94 - Place Sainte-Barbe, 1 - 1348 Louvain-la-Neuve
The evolution of strain sensors toward multifunctional and flexible devices is critical for applications like wearable technology or health monitoring. Vanadium Dioxide (VO2) has been proposed in this context to allow the simultaneous measurement of temperature and strain with sensitivity surpassing the ones of silicon. The interest in VO2 comes from its transduction mechanism relying on either a complete or partial phase change between different crystallographic states. The change between states can be triggered by physical stimulations like electrical, thermal or mechanical resulting in a change of the electrical resistance of the material. This thesis explores the potential use of VO2 for multifunctional strain sensors for flexible applications. A monolithic microfabrication scheme is presented to directly fabricate silicon and VO2 devices onto a thin polyimide-based membrane. The fabrication process allows the integration of devices without thermal budget or layer transfer. The polymer-based membrane is used to induce high-strain in the devices during a bulge test. The strain field is computed inside of the device using an FEM simulation and validated using silicon devices and Raman spectroscopy. A biaxial strain of 0.36% is reached inside the devices. The gauge factor of highly strained VO2 devices is next measured under high-strain and is observed to follow a continuous exponential increase with strain. A permanent variation of the electrical resistance of the VO2 device is observed after straining passed 0.1% which indicates clear limitations in applicable strain range of VO2 based multifunctional strain sensors.
Jury members
Prof. Jean-Pierre Raskin (UCLouvain), Supervisor
Prof. Denis Flandre (UCLouvain), Supervisor
Prof. Laurent Francis (UCLouvain), Chairperson
Prof. Dimitri Lederer (UCLouvain), Secretary
Prof. Aurelian Crunteanu (Université de Limoges, France)
Prof. Adrian Mihai Ionescu (EPFL, Suisse)