Experimental characterization of collapse-mode CMUT operation

Oralkan, Omer
Bayram, Barış
Yaralioglu, Goksen G.
Ergun, A. Sanli
Kupnik, Mario
Yeh, David T.
Wygant, Ira O.
Khuri-Yakub, Butrus T.
This paper reports on the experimental characterization of collapse-mode operation of capacitive micromachined ultrasonic transducers (CMUTs). CMUTs are conventionally operated by applying a direct current (DC) bias voltage less than the collapse voltage of the membrane, so that the membrane is deflected toward the bottom electrode. In the conventional regime, there is no contact between the membrane and the substrate; the maximum alternating current (AC) displacement occurs at the center of the membrane. In collapse-mode operation, the DC bias voltage is first increased beyond the collapse voltage, then reduced without releasing the collapsed membrane. In collapse-mode operation, the center of the membrane is always in contact with the substrate. In the case of a circular membrane, the maximum AC displacement occurs along the ring formed between the center and the edge of the membrane.


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...
Dynamic analysis of CMUTs in different regimes of operation
Bayram, Barış; Ergun, AS; Yaralioglu, GG; Khuri-Yakub, BT (2003-01-01)
This paper reports on dynamic analysis of an immersed single capacitive micromachined ultrasonic transducer (CMUT) cell transmitting. A water loaded 24 mum circular silicon membrane of a transducer was modeled. The calculated collapse and snapback voltages were 80 V and 50 V, respectively. The resonance frequency, output pressure and nonlinearity of the CMUT in three regimes of operation were determined. These regimes were: a) the conventional regime in which the membrane does not make contact with the subs...
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...
Dynamic FEM analysis of multiple cMUT cells in immersion
Bayram, Barış; Ergun, AS; Oralkan, O; Khuri-Yakub, BT (2004-01-01)
This paper reports on the accurate modeling of immersion capacitive micromachined ultrasonic transducers (cMUTs) using the time-domain, nonlinear finite element package, LS-DYNA, developed by Livermore Software Technology Corporation (LSTC). A capacitive micromachined ultrasonic transducer consists of many cMUT cells. In this paper, a square membrane was used as the unit cell to cover the transducer area by periodic replication on the surface. The silicon membrane, silicon oxide post and insulation layer we...
Citation Formats
O. Oralkan et al., “Experimental characterization of collapse-mode CMUT operation,” IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, pp. 1513–1523, 2006, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/56758.