Influence of the electrode size and location on the performance of a CMUT

Bayram, Barış
Ergun, AS
Khuri-Yakub, BT
The collapse voltage of micromachined capacitive ultrasonic transducers (CMUT) depends on the size, thickness, type, and position of the metal electrode within the membrane. This paper reports the result of a finite element study of this effect. The program (ANSYS 5.7) is used to model a circular membrane on top of a Si substrate covered by a Si3N4 insulation layer. We find that the collapse voltage increases in proportion to the metal thickness for constant membrane thickness. The collapse voltage of a membrane with a thin metal electrode decreases as the metal plate moves closer to the bottom of the membrane; whereas, for electrodes with larger metal thickness, the collapse voltage has a peak intermediate value. Decreasing the outer radius of the metal plate results in an asymptotic increase of the collapse voltage. For a finite metal thickness, an initial decrease in the collapse voltage is seen as the outer radius decreases. The collapse voltages of half-metallized and full-metallized structures are almost equal for typical metal plate thickness. The asymptotic increase of the collapse voltage is seen for ring shaped metal plates as the inner radius is varied from the center to the outer radius. In summary, we find that the influence of the metal electrode on the collapse voltage is a very important parameter in determining optimum performance of a CMUT.


Analytical calculation of collapse voltage of CMUT membrane
Nikoozadeh, A; Bayram, Barış; Yaralioglu, GG; Khuri-Yakub, BT (2004-01-01)
Because the collapse voltage determines the operating point of the capacitive micromachined ultrasonic transducer (CMUT), it is crucial to calculate and control this parameter. One approach uses parallel plate approximation, where a parallel plate motion models the average membrane displacement. This usually yields calculated collapse voltage 25 percent higher than the actual collapse voltage. More accurate calculation involves finite element method (FEM) analysis. However, depending on the required accurac...
Bayram, Barış; Kupnik, Mario; Khuri-Yakub, Butrus T. (2006-01-01)
This paper reports on the finite element analysis (FEA) of crosstalk in capacitive micromachined ultrasonic transducer (CMUT) arrays. Finite element calculations using a commercial package (LS-DYNA) were performed for an immersed I-D CMUT array operating in the conventional and collapsed modes. LS-DYNA was used to model the crosstalk in CMUT arrays under specific voltage bias and excitation conditions, and such a modeling is well worth the effort for special-purpose CMUT arrays for ultrasound applications s...
Residual stress and Young's modulus measurement of capacitive micromachined ultrasonic transducer membranes
Yaralioglu, GG; Ergun, AS; Bayram, Barış; Marentis, T; Khuri-Yakub, BT (2001-01-01)
Membranes supported by posts are used as vibrating elements of capacitive micromachined ultrasonic transducers (CMUTs). The residual stress built up during the fabrication process determines the transducer properties such as resonance frequency, collapse voltage, and gap distance. Hence, it is important to evaluate and control the stress in thin film CMUT membranes. The residual stress in the membrane causes significant vertical displacements at the center of the membrane. The stress bends the membrane post...
Computation of the electric field at a solid/gas interface in the presence of surface and volume charges
Bektas, S.I.; Farish, O.; Hizal, M. (Institution of Engineering and Technology (IET), 1986)
Enhancement of the electric field at a solid insulator/electrode/gas triple junction and on the surface of an insulator, due to imperfect contacts, surface irregularities and contamination, reduces the withstand voltage of the gas-only system. The charges deposited on the surface and in the bulk of the insulator, when stressed under high voltage, further modify the electric field. In the paper, the influence of accumulated static charges on the electric field distribution associated with a cylindrical insul...
Influence of surface treatment of fillers on the mechanical properties of thermoplastic polyurethane composites
Tayfun, Ümit; Bayramlı, Erdal; Yılmazer, Ülkü; Department of Polymer Science and Technology (2015)
The incompatibility between filler and polymer matrix is the major restriction for the production of composites to have desirable properties. Several surface modification methods are applied to filler surface in order to improve the interfacial adhesion with polymer matrix. Easy processablity and fully recyclability character of thermoplastic polyurethane (TPU) make it cost effective for many applications. Majority of TPU application is across a range of markets including automotive, sporting goods, medical...
Citation Formats
B. Bayram, A. Ergun, and B. Khuri-Yakub, “Influence of the electrode size and location on the performance of a CMUT,” 2001, Accessed: 00, 2020. [Online]. Available: