Design, fabrication, and evaluation of high frequency, single-element transducers incorporating different materials

2002 ◽  
Vol 49 (2) ◽  
pp. 169-176 ◽  
Author(s):  
K.A. Snook ◽  
Jian-Zhong Zhao ◽  
C.H.F. Alves ◽  
J.M. Cannata ◽  
Wo-Hsing Chen ◽  
...  
Keyword(s):  
High Frequency ◽  
Single Element

scholarly journals Synthetic Aperture Imaging Using High-Frequency Convex Array for Ophthalmic Ultrasound Applications

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2275
Author(s):  
Hae Gyun Lim ◽  
Hyung Ham Kim ◽  
Changhan Yoon
Keyword(s):  
Image Quality ◽  
Penetration Depth ◽  
Spatial Resolution ◽  
High Frequency ◽  
Imaging System ◽  
Ex Vivo ◽  
Synthetic Aperture ◽  
Single Element ◽  
High Frequency Ultrasound ◽  
Synthetic Aperture Imaging

High-frequency ultrasound (HFUS) imaging has emerged as an essential tool for pre-clinical studies and clinical applications such as ophthalmic and dermatologic imaging. HFUS imaging systems based on array transducers capable of dynamic receive focusing have considerably improved the image quality in terms of spatial resolution and signal-to-noise ratio (SNR) compared to those by the single-element transducer-based one. However, the array system still suffers from low spatial resolution and SNR in out-of-focus regions, resulting in a blurred image and a limited penetration depth. In this paper, we present synthetic aperture imaging with a virtual source (SA-VS) for an ophthalmic application using a high-frequency convex array transducer. The performances of the SA-VS were evaluated with phantom and ex vivo experiments in comparison with the conventional dynamic receive focusing method. Pre-beamformed radio-frequency (RF) data from phantoms and excised bovine eye were acquired using a custom-built 64-channel imaging system. In the phantom experiments, the SA-VS method showed improved lateral resolution (>10%) and sidelobe level (>4.4 dB) compared to those by the conventional method. The SNR was also improved, resulting in an increased penetration depth: 16 mm and 23 mm for the conventional and SA-VS methods, respectively. Ex vivo images with the SA-VS showed improved image quality at the entire depth and visualized structures that were obscured by noise in conventional imaging.

Intraocular Pressure–dependent Corneal Elasticity Measurement Using High-frequency Ultrasound

2019 ◽  
Vol 41 (5) ◽  
pp. 251-270 ◽  
Author(s):  
Laurentius O. Osapoetra ◽  
Dan M. Watson ◽  
Stephen A. McAleavey
Keyword(s):  
Intraocular Pressure ◽  
High Resolution ◽  
High Frequency ◽  
Wave Speed ◽  
Biomechanical Properties ◽  
Single Element ◽  
High Frequency Ultrasound ◽  
Spatially Resolved ◽  
Corneal Biomechanical Properties ◽  
Frequency Ultrasound

Measurement of corneal biomechanical properties can aid in predicting corneal responses to diseases and surgeries. For delineation of spatially resolved distribution of corneal elasticity, high-resolution elastography system is required. In this study, we demonstrate a high-resolution elastography system using high-frequency ultrasound for ex-vivo measurement of intraocular pressure (IOP)-dependent corneal wave speed. Tone bursts of 500 Hz vibrations were generated on the corneal surface using an electromagnetic shaker. A 35-MHz single-element transducer was used to track the resulting anti-symmetrical Lamb wave in the cornea. We acquired spatially resolved wave speed images of the cornea at IOPs of 7, 11, 15, 18, 22, and 29 mmHg. The IOP dependence of corneal wave speed is apparent from these images. Statistical analysis of measured wave speed as a function of IOP revealed a linear relation between wave speed and IOP cs = 0.37 + 0.22 × IOP, with the coefficient of determination R2 = 0.86. We also observed depth-dependent variations of wave speed in the cornea, decreasing from anterior toward posterior. This depth dependence is more pronounced at higher IOP values. This study demonstrates the potential of high-frequency ultrasound elastography in the characterization of spatially resolved corneal biomechanical properties.

10F-4 Self-Focused 1-3 Composite LiNbO3 Single Element Transducers for High Frequency HIFU Applications

2007 ◽  
Author(s):  
Ruibin Liu ◽  
Hyung Ham Kim ◽  
J.M. Cannata ◽  
Gin-Shin Chen ◽  
K.K. Shung
Keyword(s):  
High Frequency ◽  
Single Element

scholarly journals ZnO thin-film optimization towards the fabrication of high-frequency ultrasound transducers

2021 ◽  
Author(s):  
◽  
Ihab Sinno
Keyword(s):  
Zinc Oxide ◽  
High Frequency ◽  
Oxide Films ◽  
Single Element ◽  
High Deposition Rate ◽  
Ultrasound Transducers ◽  
Metal Contacts ◽  
High Frequency Ultrasound ◽  
Zinc Oxide Films ◽  
Frequency Ultrasound

<p>Zinc oxide is a popular wide bandgap semiconductor material with versatile electrical and optical properties. In its wurtzite crystal form, this semiconductor is piezoelectric, and has material properties that make it an attractive candidate for fabricating high frequency ultrasound transducers. This thesis describes the development of an RF sputtering process for creating zinc oxide films with thicknesses ranging from 3μm to 10μm, aiming for transducer frequencies of 300MHz to 1 GHz. Sputtering parameters are optimized to meet the dual requirements of a c-axis film orientation while maintaining a high deposition rate. These constraints and the dimensional characteristics of the utilized sputtering system, such as the short substrate-to-target distance, introduce high levels of strain in the deposited zinc oxide films. Various anneal procedures are developed to reduce film strain and optimize the resulting microstructure. It is found that annealing temperatures > 600°C eliminate the inherent film strain, but simultaneously result in the dewetting of the bottom metal contact, making this thermal treatment unsuitable for device processing. As an alternative to traditional metal contacts used in ultrasound transducers, the use of highly doped zinc oxide contacts is then investigated. It is shown that aluminium doped zinc oxide contacts provide an improved seed layer for device growth while eliminating the dewetting problems associated with metal contacts at high anneal temperatures. In addition, the use of such transparent conductive oxide contacts can lead to novel ultrasound applications, which benefit from the integration of optical and acoustic imaging in a single lens. A proof of concept all-zinc oxide single element ultrasound transducer structure is finally fabricated, to highlight the potential of an integrated optical-acoustic lens design.</p>

scholarly journals Implementation of a Rotational Ultrasound Biomicroscopy System Equipped with a High-Frequency Angled Needle Transducer — Ex Vivo Ultrasound Imaging of Porcine Ocular Posterior Tissues

2021 ◽  
Author(s):  
Tae-Hoon Bok ◽  
Juho Kim ◽  
Jinho Bae ◽  
Chong Hyun Lee ◽  
Dong-Guk Paeng
Keyword(s):  
Ultrasound Imaging ◽  
High Frequency ◽  
Ex Vivo ◽  
Focal Length ◽  
Ultrasound Biomicroscopy ◽  
Single Element ◽  
High Frequency Ultrasound ◽  
Scanning Angle ◽  
Distance Range ◽  
Minimal Incision

The mechanical scanning of a single element transducer has been mostly utilized for high-frequency ultrasound imaging. However, it requires space for the mechanical motion of the transducer. In this paper, a rotational scanning ultrasound biomicroscopy (UBM) system equipped with a high-frequency angled needle transducer is designed and implemented in order to minimize the space required. It was applied to ex vivo ultrasound imaging of porcine posterior ocular tissues through a minimal incision hole of 1 mm in diameter. The retina and sclera for the one eye were visualized in the relative rotating angle range of 270° ~ 330° and at a distance range of 6 ~ 7 mm, whereas the tissues of the other eye were observed in relative angle range of 160° ~ 220° and at a distance range of 7.5 ~ 9 mm. The layer between retina and sclera seemed to be bent because the distance between the transducer tip and the layer was varied while the transducer was rotated. Certin features of the rotation system such as the optimal scanning angle, step angle and data length need to be improved for ensure higher accuracy and precision. Moreover, the focal length should be considered for the image quality. This implementation represents the first report of a rotational scanning UBM system.

scholarly journals Implementation of a Rotational Ultrasound Biomicroscopy System Equipped with a High-Frequency Angled Needle Transducer — Ex Vivo Ultrasound Imaging of Porcine Ocular Posterior Tissues

2021 ◽  
Author(s):  
Tae-Hoon Bok ◽  
Juho Kim ◽  
Jinho Bae ◽  
Chong Hyun Lee ◽  
Dong-Guk Paeng
Keyword(s):  
Ultrasound Imaging ◽  
High Frequency ◽  
Ex Vivo ◽  
Focal Length ◽  
Ultrasound Biomicroscopy ◽  
Single Element ◽  
High Frequency Ultrasound ◽  
Scanning Angle ◽  
Distance Range ◽  
Minimal Incision

The mechanical scanning of a single element transducer has been mostly utilized for high-frequency ultrasound imaging. However, it requires space for the mechanical motion of the transducer. In this paper, a rotational scanning ultrasound biomicroscopy (UBM) system equipped with a high-frequency angled needle transducer is designed and implemented in order to minimize the space required. It was applied to ex vivo ultrasound imaging of porcine posterior ocular tissues through a minimal incision hole of 1 mm in diameter. The retina and sclera for the one eye were visualized in the relative rotating angle range of 270° ~ 330° and at a distance range of 6 ~ 7 mm, whereas the tissues of the other eye were observed in relative angle range of 160° ~ 220° and at a distance range of 7.5 ~ 9 mm. The layer between retina and sclera seemed to be bent because the distance between the transducer tip and the layer was varied while the transducer was rotated. Certin features of the rotation system such as the optimal scanning angle, step angle and data length need to be improved for ensure higher accuracy and precision. Moreover, the focal length should be considered for the image quality. This implementation represents the first report of a rotational scanning UBM system.

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