The Effect of Evacuated Backside Cavity on the Dynamic Characteristics of a Capacitive Micromachined Ultrasonic Transducer

Ahmad , Babar and Pratap, Rudra (2009) The Effect of Evacuated Backside Cavity on the Dynamic Characteristics of a Capacitive Micromachined Ultrasonic Transducer. In: International Conference on MEMS (ICMEMS 2009), January 3-5, 2009, IIT Madras.

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Abstract

In this paper, we investigate the effect of vacuum sealing the backside cavity of a Capacitive Micromachined Ultrasonic Transducer (CMUT). The presence or absence of air inside the cavity has a marked effect upon the system parameters, such as the natural frequency, damping, and the pull-in voltage. The presence of vacuum inside the cavity of the device causes a reduction in the effective gap height which leads to a reduction in the pull-in voltage. We carry out ANSYS simulations to quantify this reduction. The presence of vacuum inside the cavity of the device causes stress stiffening of the membrane, which changes the natural frequency of the device. A prestressed modal analysis is carried out to determine the change in natural frequency due to stress stiffening. The equivalent circuit method is used to evaluate the performance of the device in the receiver mode. The lumped parameters of the device are obtained and an equivalent circuit model of the device is constructed to determine the open circuit receiving sensitivity of the device. The effect of air in the cavity is included by incorporating an equivalent compliance and an equivalent resistance in the equivalent circuit.

Item Type:	Conference Paper
Publisher:	Springer
Additional Information:	Copyright of this article belongs to Springer.
Keywords:	Capacitive Micromachined Ultrasonic Transducer (CMUT);Equivalent circuits;Lumped parameters;Pull-in voltage;Stress stiffening
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	19 Dec 2011 09:49
Last Modified:	19 Dec 2011 09:49
URI:	http://eprints.iisc.ac.in/id/eprint/40100

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