Design of embedded micro-heaters for high-temperature quartz resonators

The research aims to enhance the maximum operating temperature of quartz crystal microbalances for thermogravimetric analysis through an innovative design of thin-film micro-heaters integrated on quartz disc resonators. The study focuses on developing a device with an optimised layout that provides simultaneous sensing (temperature around the electrode area) and actuating (heating) capabilities, minimising heater-induced thermoelastic stresses while extending the operating temperature up to and above 300 °C, the current limit of the state-of-the-art available QCM (Quartz Crystal Microbalance) technology with localised heating. A finite element model of the crystal with a parametric heater layout was developed to guide the design and the related optimisation phase, which evaluated various geometries based on key criteria, including temperature uniformity and thermoelastic stress distribution. A design methodology is presented to achieve optimal temperature uniformity, reduce thermoelastic stresses, and prevent quartz substrate failure or permanent admittance signal loss. Preliminary experiments confirmed that the proposed micro-heater layouts enable the QCMs to operate up to 350 °C, enabling in-situ high-temperature thermo-gravimetric studies.