Radiation impedance of an array of circular capacitive micromachined ultrasonic transducers

Senlik, M.N.; Ölçüm, Selim; Köymen, H.; Atalar, Abdullah

doi:10.1109/tuffc.2010.1501

Cited by 48 publications

(37 citation statements)

References 25 publications

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“…Therefore, the equivalent radiation impedance is somewhat lower. The radiation impedance for such an array of CMUT membranes is calculated in [6] for the uncollapsed mode. It is shown that the normalized radiation impedance approaches to 1 2 ρ 0 c when the array is sufficiently large.…”

Section: Resultsmentioning

confidence: 99%

“…It is shown that the normalized radiation impedance approaches to 1 2 ρ 0 c when the array is sufficiently large. Therefore, for comparing the results of the equivalent circuit simulations to experimental results obtained from fabricated devices, we use half the radiation resistance of the fully loaded case as shown in [6].…”

Section: Resultsmentioning

confidence: 99%

“…The radiation impedance of a circular, clamped membrane of radius a for the uncollapsed mode was calculated earlier [6]. It was shown that for large ka values, the radiation impedance approaches to…”

Section: Fig 2 (Dashed Curves)mentioning

confidence: 99%

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An equivalent circuit for collapse operation mode of CMUTs

Ölçüm

Yamaner

Bozkurt

et al. 2010

2010 IEEE International Ultrasonics Symposium

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Abstract-Collapse mode of operation of the capacitive micromachined ultrasonic transducers (CMUTs) was shown to be a very effective way for achieving high output pressures. However, no accurate model exists for understanding the mechanics and limits of the collapse mode. In this work, we extend the analyses made for CMUTs working in uncollapsed mode to collapsed mode. We have developed an equivalent nonlinear electrical circuit that can accurately simulate the mechanical behavior of a CMUT under any large signal electrical excitation. The static and dynamic deflections of a membrane predicted by the model are compared with the finite element simulations. The equivalent circuit model can estimate the static deflection within 1% and the transient behavior of a CMUT membrane within 3% accuracy. The circuit model is also compared to experimental results of pulse excitation applied to fabricated collapse mode CMUTs. The model is suitable as a powerful design and optimization tool for the collapsed as well as the uncollapsed case of CMUTs.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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An equivalent circuit for collapse operation mode of CMUTs

Ölçüm

Yamaner

Bozkurt

et al. 2010

2010 IEEE International Ultrasonics Symposium

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“…It is important to note that the radiation impedance is frequency dependent and it is not purely real. It depends on the membrane profile, the number and positions of CMUT cells [4]. In this circuit model, we worked on two different element configurations: one with a single CMUT cell and the other with an array of seven CMUT cells.…”

Section: A Radiation Impedancementioning

confidence: 99%

Optimizing CMUT geometry for high power

Yamaner

Ölçüm

Bozkurt

et al. 2010

2010 IEEE International Ultrasonics Symposium

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Abstract-Capacitive micromachined ultrasonic transducers (CMUTs) have demonstrated various advantages over piezoelectric transducers. However, current CMUT designs produce low output pressures with high harmonic distortions. Optimizing the transducer parameters requires an iterative solution and is too time consuming using finite element (FEM) modelling tools. In this work, we present a method of designing high output pressure CMUTs with relatively low distortion. We analyze the behavior of a membrane under high voltage continuous wave operation using a nonlinear electrical circuit model. The radiation impedance of an array of CMUTs is accurately represented using an RLC circuit in the model. The maximum membrane swing without collapse is targeted in the transmit mode. Using SPICE simulation of the parametric circuit model, we design the CMUT cell with optimized parameters such as the membrane radius (a), thickness (tm), insulator thickness (ti) and gap height (tg). The model also predicts the amount of second harmonic at the output. To verify the accuracy of the results, we built a FEM model with the same CMUT parameters. The design starts by choosing ti for the given input voltage level. First, a is selected for the maximum radiation resistance of the array at the operating frequency. Second, tm is found for the resonance at the input frequency. Third, tg is chosen for the maximum membrane swing. Under this condition, a frequency shift in the resonant frequency occurs. Second and third steps are repeated until convergence. This method results in a CMUT array with a high output power and with low distortion.

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“…Caronti 10 reported FEA results on a 1-D CMUT array and presented that the mutual acoustic impedance through the liquid represented a major source of the cross coupling. Senlik 11 focused on the lumped acoustic impedance of CMUTs with several design parameters. Meynier 12 presented the analytic calculation of CMUTs, having a periodic pattern of plates.…”

Section: Introductionmentioning

confidence: 99%

Dynamic response of an array of flexural plates in acoustic medium

Park

Khuri‐Yakub

2012

The Journal of the Acoustical Society of America

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The dynamic response of a transducer array made up of circular flexural plates in immersion is analytically calculated. The calculation method includes three steps: (1) the calculation of parallel resonant frequency and the velocity profile of each plate, (2) the calculation of mutual acoustic impedance between the plates, and (3) the calculation of velocity response, including the mechanical and acoustic impedance. The calculation method is validated by both finite element analysis and measurement results of a fabricated capacitive micromachined ultrasonic transducer. Based on the calculated velocity, the near-field pressure and the near-to-far field radiation patterns are presented. The flexural plate array in immersion displays two modes of operation. At low frequency, the mode shape of the transducer array is similar to that of a suspended plate and, at certain frequencies, two groups of plates move in opposite phase, which results in the cancellation of the average velocity. At high frequency, the mode shape is similar to that of a piston transducer; however, the near-field pressure distribution is similar to that of a resilient disk.

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Radiation impedance of an array of circular capacitive micromachined ultrasonic transducers

Cited by 48 publications

References 25 publications

An equivalent circuit for collapse operation mode of CMUTs

An equivalent circuit for collapse operation mode of CMUTs

Optimizing CMUT geometry for high power

Dynamic response of an array of flexural plates in acoustic medium

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