A New Advanced Analytical Model for Bi-Layer Circular CMUT-Based Gas Sensors

Capacitive Micromachined Ultrasonic Transducers (CMUTs) have been introduced as an alternative candidate to piezoelectric transducers for ultrasonic imaging applications due to their better acoustic matching and higher bandwidth. In this paper and in an unconventional approach, a CMUT configuration is used as a highly-sensitive gas sensor that operates based on the measured frequency shifts in response to the mass of absorbed target analytes. In this work, a new complex bi-layer CMUT gas sensor model is developed that comprises the effect of sensing material properties as well as the sensor structural materials and geometrical design parameters to optimize and enhance the sensor sensitivity based on the application. The proposed analytical model is further utilized to design a high-sensitivity CMUT sensor for low concentration detection of gas molecules. The analytical model analysis and finite element method simulations are also conducted and compared. The results show a high achieved sensitivity of 364 Hz/zg for this sensor. In addition, the results indicate less than 2% variation between the developed analytical bi-layer model and the FEA multiphysics simulations
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