A fluid-coupled transmitting CMUT operated in collapse mode: Semi-analytic modeling and experiments

Pekař, Martin; Nispen, S.H.M. van; Fey, Rhb Rob; Shulepov, Sergei; Mihajlović, Nenad; Nijmeijer, Henk

doi:10.1016/j.sna.2017.09.055

Cited by 6 publications

(4 citation statements)

References 33 publications

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“…In this paper, pre-charged collapse-mode CMUTs were studied through modeling and characterization of four device variants (A, B, C and D) with an Al 2 O 3 layer between the top and bottom electrodes. To study their charging behavior, a semi-analytic reduced order model was developed following the approach of [22]. The model includes the built-in charging layer as an additional force term.…”

Section: Discussionmentioning

confidence: 99%

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Modeling and Characterization of Pre-Charged Collapse-Mode CMUTs

Saccher

Kawasaki

Klootwijk

et al. 2023

IEEE Open J. Ultrason., Ferroelect., Freq. Contr.

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Recently, the applications of ultrasound transducers expanded from high-end diagnostic tools to point of care diagnostic devices and wireless power receivers for implantable devices. These new applications additionally require that the transducer technology must comply to biocompatibility and manufacturing scalability. In this respect, Capacitive Micromachined Ultrasound Transducers (CMUTs) have a strong advantage compared to the conventional PZT based transducers. However, current CMUTs require a large DC bias voltage for their operation, which limits the miniaturizability of these devices. In this study, we propose a pre-charged collapse-mode CMUT for immersive applications that can operate without an external bias by means of a charge trapping Al 2 O 3 layer embedded in the dielectrics between the top and bottom electrodes. The built-in charge layer was analytically modeled and four layer stack combinations were investigated and characterized. The measurement results of the CMUTs were then used to fit the model and to quantify the amount and type of trapped charge. It was found that these devices polarize due to the ferroelectric-like behavior of the Al 2 O 3 , and the amount of charge stored in the charge-trapping layer was estimated to be approximately 0.02 C/m 2 . Their acoustic performance shows a transmit and receive sensitivity of 8.8 kPa/V and 13.1 V/MPa respectively. In addition, we show that increasing the charging temperature, the charging duration, and the charging voltage results in a higher amount of stored charge. Finally, results of ALT tests showed that these devices have a lifetime of more than 2.5 years at body temperature. CMUT, zero-bias CMUTs, collapse-mode CMUTs, ultrasound transducer INDEX TERMS

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Section: Discussionmentioning

confidence: 99%

“…where t i , is the thickness of the dielectric layers between the top and bottom electrodes divided by their corresponding dielectric constants. For further details, readers are referred to [22]. In this work, (1) was adapted by adding the electrostatic force from the built-in charge.…”

Section: Modeling the Pre-charged Cmutmentioning

confidence: 99%

Modeling and Characterization of Pre-Charged Collapse-Mode CMUTs

Saccher

Kawasaki

Klootwijk

et al. 2023

IEEE Open J. Ultrason., Ferroelect., Freq. Contr.

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“…The membrane deflection was small and the mid-plane of the membrane was assumed with no elongation, and the governing differential equation was solved using the Galerkin method. The results were compared with experimental results with a satisfactory accuracy [ 64 ].

where

was the effective indentation hardness,

was the complementary error function,

was the standard deviation of the combined surface roughness, and

was the residual stress parameter.…”

Section: Static Membrane Deflection Modelsmentioning

confidence: 99%

A Review on Analytical Modeling for Collapse Mode Capacitive Micromachined Ultrasonic Transducer of the Collapse Voltage and the Static Membrane Deflections

Wang

Liu²,

et al. 2021

Micromachines

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Analytical modeling of capacitive micromachined ultrasonic transducer (CMUT) is one of the commonly used modeling methods and has the advantages of intuitive understanding of the physics of CMUTs and convergent when modeling of collapse mode CMUT. This review article summarizes analytical modeling of the collapse voltage and shows that the collapse voltage of a CMUT correlates with the effective gap height and the electrode area. There are analytical expressions for the collapse voltage. Modeling of the membrane deflections are characterized by governing equations from Timoshenko, von Kármán equations and the 2D plate equation, and solved by various methods such as Galerkin’s method and perturbation method. Analytical expressions from Timoshenko’s equation can be used for small deflections, while analytical expression from von Kármán equations can be used for both small and large deflections.

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“…Numerous efforts have been undertaken over the years to address the performance issues of CMUTs and circumvent the associated trade-off in their conventional design. These endeavors have included the introduction of a collapse-snapback mode of operation and the incorporation of dual electrodes within the CMUT membrane. − …”

Section: Introductionmentioning

confidence: 99%

Capacitive Micromachined Ultrasonic Transducer (CMUT) Made with SWCNTs/Parylene-C Composite Membranes

Liu

Luo

et al. 2023

ACS Appl. Electron. Mater.

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Traditional CMUTs are fabricated from silicon-based membranes. However, the poor flexibility and high cost of silicon-based membranes have resulted in low output pressure and high manufacturing costs for the fabricated CMUTs. Here, we report the feasibility of a type of single-walled carbon nanotubes (SWCNTs)/Parylene-C composite membrane for the fabrication of a CMUT. The innovative aspect of this method is the replacement of traditional silicon-based membranes with SWCNTs/Parylene-C composite membranes, which can simplify the process and reduce manufacturing costs. The SWCNTs/Parylene-C composite membrane has a Young's modulus of 4.4 GPa and a surface resistivity of 29.6 Ω/sq. Prior to bonding, oxygen plasma treatment is performed on the SWCNTs/Parylene-C composite membrane and SU-8 surface to introduce functional groups such as hydroxyl and carboxyl, which aid in bonding. The resonance frequency of the fabricated CMUT is 2.108 MHz, and the quality factor is 52.6. The results suggest that the SWCNTs/Parylene-C composite membrane has potential for use in CMUT fabrication due to its excellent mechanical and electrical properties. The study provides a direction for the development of CMUTs with improved performance and may have significant applications in fields such as medical imaging and wearable health monitoring devices.

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A fluid-coupled transmitting CMUT operated in collapse mode: Semi-analytic modeling and experiments

Cited by 6 publications

References 33 publications

Modeling and Characterization of Pre-Charged Collapse-Mode CMUTs

Modeling and Characterization of Pre-Charged Collapse-Mode CMUTs

A Review on Analytical Modeling for Collapse Mode Capacitive Micromachined Ultrasonic Transducer of the Collapse Voltage and the Static Membrane Deflections

Capacitive Micromachined Ultrasonic Transducer (CMUT) Made with SWCNTs/Parylene-C Composite Membranes

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