Resonant and Antiresonant Frequencies Behavior with Temperature Changes in Gravimetric Sensors

Gravimetric sensing with high accuracy is one of the challenges of the electroacoustic technology. Thin film bulk acoustic wave resonators have boosted the performance of their quartz crystal microbalances predecessors in terms of mass sensitivity and resolution. However, problems regarding their sensitivity to different environmental factors, not only mass attachment to their surface, still exist. One of the most studied issues is the influence of the surrounding temperature on their frequency response, i.e. their thermal coefficient of frequency (TCF). There exist different methods to reduce the TCF, hence the response of the sensor to temperature, or to accurately monitor both mass and temperature influences. These include TCF compensation, dual-mode devices with different TCFs or using a reference sensor. Here we propose using a simple method based on single-mode AIN-based solidly mounted resonators to monitor both temperature changes and mass detection. We do so by monitoring both resonant and antiresonant frequencies, which have different TCFs but same mass sensitivities, being able to discriminate if a temperature variation occurred during a gravimetric sensing event.