In this paper we present a structural analytical model for a capacitive micromachined ultrasonic transducer (CMUT), based on a sacrificial release fabrication process and comprised of electro-mechanical plate actuators transferring their motion to a coupling roof structure on top. The structure features a larger average displacement compared to conventional designs at lower operational frequencies. Low operational frequencies in the range of 40 kHz to 1 MHz are beneficial for airborne applications due to their frequency-dependent strong wave attenuation in air, limiting the signal-to-noise ratio. The eigenfrequency in dependence of the roof mass is calculated analytically and lumped elements, which can be used in equivalent circuits, are extracted. In addition, finite element analyses utilizing a shell-beam model are conducted. Experimental results, based on digital holographic microscopy, reveal the usability of the deduced model within an uncertainty of 8 %. The developed dimensionless form of the analytical model can be used for future design purposes.

In this paper we present a structural analytical model for a capacitive micromachined ultrasonic transducer (CMUT), based on a sacrificial release fabrication process and comprised of electro-mechanical plate actuators transferring their motion to a coupling roof structure on top. The structure features a larger average displacement compared to conventional designs at lower operational frequencies. Low operational frequencies in the range of 40 kHz to 1 MHz are beneficial for airborne applications due to their frequency-dependent strong wave attenuation in air, limiting the signal-to-noise ratio. The eigenfrequency in dependence of the roof mass is calculated analytically and lumped elements, which can be used in equivalent circuits, are extracted. In addition, finite element analyses utilizing a shell-beam model are conducted. Experimental results, based on digital holographic microscopy, reveal the usability of the deduced model within an uncertainty of 8 %. The developed dimensionless form of the analytical model can be used for future design purposes.

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