Single- PZT- Fiber Transducers for 3D Ultrasound Computed Tomography: Characterization and Modeling

Angerer, Martin; Zapf, Michael; Gebhardt, Sylvia; Ruiter, Nicole V.

doi:10.1109/ius54386.2022.9958428

Cited by 6 publications

(7 citation statements)

References 11 publications

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“…For each simulation, the -6 dB opening angle was extracted from the far field directional response in the lateral plane. A width of 1 mm provides a minimum opening angle of 54 • at 2 MHz, which is comparable to the 43 • -10 dB opening angle at 2.6 MHz achieved by other UST systems [27], indicating that this is a suitable beam pattern for UST imaging.…”

Section: Pzt Element Selectionsupporting

confidence: 60%

“…The nominal opening angle of 55.4 • is smaller than the predicted value of 95.1 • at 1.22 MHz from Figure 2A, which could be due to the strong lateral resonance modifying the radiating pressure, producing an effective source width larger than the physical extent of the elements [36]. However, this opening angle is suitable for imaging, since it is similar to the 43 • (-10 dB at 2.6 MHz) [27] opening angle reported for another UST system.…”

Section: Beamwidth Opening Angle and Angle Dependent Frequency Responsementioning

confidence: 71%

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open-UST: An Open-Source Ultrasound Tomography Transducer Array System

Roberts¹,

Martin²,

Brown³

et al. 2023

Preprint

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Fast imaging methods are needed to promote widespread clinical adoption of Ultrasound Tomography (UST), and more widely available UST hardware could support the experimental validation of new measurement configurations. In this work, an open-source 256-element transducer ring array was developed (morganjroberts.github.io/open-UST) and manufactured using rapid prototyping, for only £2k. Novel manufacturing techniques were used, resulting in a 1.17 • mean beam axis skew angle, a 104 µm mean element position error, and a ±13.6 µm deviation in matching layer thickness. The nominal acoustic performance was measured using hydrophone scans and watershot data, and the 61.2 dB SNR, 55.4 • opening angle, 16.3 mm beamwidth and 54% transmit-receive bandwidth (-12 dB), were found to be similar to existing systems, and compatible with full waveform inversion reconstruction methods. The inter-element variation in acoustic performance was typically <10% without using normalisation, meaning that the elements can be modelled identically during image reconstruction, removing the need for individual source definitions based on hydrophone measurements. Finally, data from a phantom experiment was successfully reconstructed. These results demonstrate that the open-UST system is accessible for users, and suitable for UST imaging research.

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Section: Pzt Element Selectionsupporting

confidence: 60%

Section: Beamwidth Opening Angle and Angle Dependent Frequency Responsementioning

confidence: 71%

open-UST: An Open-Source Ultrasound Tomography Transducer Array System

Roberts¹,

Martin²,

Brown³

et al. 2023

Preprint

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“…New imaging approaches require transducer technologies to facilitate a large design freedom, cost-effective production and excellent acoustic performance. With the commonly used piezoelectric transducers, these requirements can be hard to achieve [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Hence, to accurately meet specific transducer requirements, these effects have to be considered in the CMUT element design process. In previous work, we presented the analysis of hexagonal elements consisting of 127 cells using a FE model [22]. A good fit between measurement and model was achieved in terms of acoustic performance.…”

Section: Introductionmentioning

confidence: 99%

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Studying the Effects of Mutual Acoustic Impedance on the Performance of Polymer-Based CMUTs

Angerer,

Welsch,

Gerardo

et al. 2024

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

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The objective of this work was to investigate changes in the acoustic characteristics of micromachined transducers caused by acoustic cross-coupling between cells. We used hexagonal, polymer-based capacitive micromachined ultrasonic transducers (polyCMUTs) consisting of 127 cells connected in parallel. The distances between the cells were varied, while the cell dimensions and number of cells remained constant. The resulting changes in characteristics were evaluated in terms of peak frequency f pk , fractional bandwidth F BW , peak transmit sensitivity S pk and opening angle Φ t . The study relies on results from an analytic multicell model (MCM) which considers cross-coupling effects between cells through a mutual acoustic impedance matrix. The results are compared with finite element (FE) analyses and measurements on fabricated prototypes. The manufacturing processes used to produce the polyCMUT prototypes are explained in detail. We found significant changes in all acoustic characteristics: as cell spacing increases, f pk and Φ t decrease, while S pk gradually rises to about twice the initial value. The F BW varies due to the change in f pk , peaking at small to intermediate cell-to-cell distances. While both modeling approaches cover the general effects, discrepancies in comparison to the measurements were identified. The FE model provided better fits than the analytic MCM, albeit at significantly higher computational costs. The effects on the acoustic characteristics were found strongest at lower frequencies and if many cells are in close proximity to each other. Hence, rotational symmetric or square transducers operating at lower frequencies are affected most. The results demonstrate that design approaches based on modeling single cells may lead to significant deviations from design goals. Both, analytic and FE models are suitable tools to estimate the effects of acoustic interactions and to predict the performance. This aids in meeting design requirements of micromachined ultrasound transducers consisting of multiple radiators.

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