Articles techniques et présentations

The goal of this study is to exploit the phase change in vanadium dioxide (VO₂) for optical sensing. Infrared (IR) sensing is of paramount interest for next-generation Internet of Things (IoT) devices. Phase change materials (PCMs) are expected to enable low-energy consumption sensors, making them ideal for IoT applications. Especially VO2 transitions from an insulating phase to a metallic phase at round 70°C making it suitable for near room-temperature sensors. Plasmonic photothermal conversion allows for tuning the operational wavelength of these sensors by simply adjusting the spacing, shape, or material of an array of metallic or dielectric/metallic nanoparticules (NP) or micropatterns (MP) structured on the surface of the VO2 active layer. When light activates the localized surface plasmon resonance (LSPR), overall light absorption increases. Part of the light is scattered by the nano- or micro-structures, while the rest is absorbed and converted into heat. We present a simulation of a device where a near-to-medium wavelength IR input plane wave is converted into heat through LSPR which is expected to trigger the phase change in VO2. To operate the device at ambient temperature, an electrical bias will be applied to the VO2 resistor to ease its phase transition. Various parameters, such as layer thickness, material composition, NP/MP shapes, and periodicity, can be optimized to maximize photothermal sensitivity and specificity. Simulating VO₂ is still challenging because its phase transition from an insulating to a metallic state is influenced by multiple factors, including voltage, temperature, and strain. We use COMSOL Multiphysics® to simulate this multiphysics problem, incorporating electromagnetic waves, heat transfer in solids, and electrical modules for our simulations. This work is done within the frame of SWIMS ERC Synergy project. We expect to derive design insight for maximising the absorbance for the plasmonic enhanced photothermal conversion to activate the VO2’s phase transition.