scholarly journals Multielement Ring Array Based on Minute Size PMUTs for High Acoustic Pressure and Tunable Focus Depth

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4786
Author(s):  
Eyglis Ledesma ◽  
Iván Zamora ◽  
Arantxa Uranga ◽  
Núria Barniol
Keyword(s):  
Ultrasound Imaging ◽  
High Performance ◽  
Ultrasound Image ◽  
Equivalent Diameter ◽  
Central Ring ◽  
Output Pressure ◽  
Beam Focusing ◽  
Annular Array ◽  
Resolution Imaging ◽  
Pulse Echo

This paper presents a multielement annular ring ultrasound transducer formed by individual high-frequency PMUTs (17.5 MHz in air and 8.7 MHz in liquid) intended for high-precision axial focalization and high-performance ultrasound imaging. The prototype has five independent multielement rings fabricated by a monolithic process over CMOS, allowing for a very compact and robust design. Crosstalk between rings is under 56 dB, which guarantees an efficient beam focusing on a range between 1.4 mm and 67 µm. The presented PMUT-on-CMOS annular array with an overall diameter down to 669 µm achieves an output pressure in liquid of 4.84 kPa/V/mm2 at 1.5 mm away from the array when the five channels are excited together, which is the largest reported for PMUTs. Pulse-echo experiments towards high-resolution imaging are demonstrated using the central ring as a receiver. With an equivalent diameter of 149 µm, this central ring provides high receiving sensitivity, 441.6 nV/Pa, higher than that of commercial hydrophones with equivalent size. A 1D ultrasound image using two channels is demonstrated, with maximum received signals of 7 mVpp when a nonintegrated amplifier is used, demonstrating the ultrasound imaging capabilities.

scholarly journals Generation of terahertz vector beams using dielectric metasurfaces via spin-decoupled phase control

Nanophotonics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 3393-3402 ◽  
Author(s):  
Yuehong Xu ◽  
Huifang Zhang ◽  
Quan Li ◽  
Xueqian Zhang ◽  
Quan Xu ◽  
...  
Keyword(s):  
High Performance ◽  
Special Kind ◽  
Phase Control ◽  
High Resolution Imaging ◽  
Plasmon Excitation ◽  
Bessel Beams ◽  
Dynamic Phase ◽  
Vector Beams ◽  
Resolution Imaging ◽  
Spatially Variant

AbstractCylindrical vector beams (CVBs), being a special kind of beams with spatially variant states of polarizations, are promising in photonics applications, including high-resolution imaging, plasmon excitation, optical trapping, and laser machining. Recently, generating CVBs using metasurfaces has drawn enormous interest owing to their highly designable, multifunctional, and integratable features. However, related studies remain unexplored in the terahertz regime. Here, a generic method for efficiently generating terahertz CVBs carrying orbital angular momentums (OAMs) is proposed and experimentally demonstrated using transmission-type spatial-variant dielectric metasurfaces, which is realized by designing the interference between the two circularly polarized transmission components. This method is based on spin-decoupled phase control allowed by simultaneously manipulating the dynamic phase and geometric phase of each structure, endowing more degree of freedom in designing the vector beams. Two types of metasurfaces which respectively generate polarization-dependent terahertz vector vortex beams (VVBs) and vector Bessel beams (VBBs) are experimentally characterized. The proposed method opens a new window to generate versatile vector beams, providing new capabilities in developing novel, compact, and high-performance devices applicable to broad electromagnetic spectral regimes.

scholarly journals Reverse Scan Conversion and Efficient Deep Learning Network Architecture for Ultrasound Imaging on a Mobile Device

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2629
Author(s):  
Kunkyu Lee ◽  
Min Kim ◽  
Changhyun Lim ◽  
Tai-Kyong Song
Keyword(s):  
Deep Learning ◽  
Ultrasound Imaging ◽  
Mobile Device ◽  
Network Architecture ◽  
Point Of Care ◽  
Ultrasound Image ◽  
Training Dataset ◽  
Point Of Care Ultrasound ◽  
Reverse Scan ◽  
Scan Conversion

Point-of-care ultrasound (POCUS), realized by recent developments in portable ultrasound imaging systems for prompt diagnosis and treatment, has become a major tool in accidents or emergencies. Concomitantly, the number of untrained/unskilled staff not familiar with the operation of the ultrasound system for diagnosis is increasing. By providing an imaging guide to assist clinical decisions and support diagnosis, the risk brought by inexperienced users can be managed. Recently, deep learning has been employed to guide users in ultrasound scanning and diagnosis. However, in a cloud-based ultrasonic artificial intelligence system, the use of POCUS is limited due to information security, network integrity, and significant energy consumption. To address this, we propose (1) a structure that simultaneously provides ultrasound imaging and a mobile device-based ultrasound image guide using deep learning, and (2) a reverse scan conversion (RSC) method for building an ultrasound training dataset to increase the accuracy of the deep learning model. Experimental results show that the proposed structure can achieve ultrasound imaging and deep learning simultaneously at a maximum rate of 42.9 frames per second, and that the RSC method improves the image classification accuracy by more than 3%.

scholarly journals Nanocone-Shaped Carbon Nanotubes Field-Emitter Array Fabricated by Laser Ablation

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3244
Author(s):  
Jiuzhou Zhao ◽  
Zhenjun Li ◽  
Matthew Thomas Cole ◽  
Aiwei Wang ◽  
Xiangdong Guo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Laser Ablation ◽  
High Performance ◽  
Low Cost ◽  
Field Emitter ◽  
Beam Focusing ◽  
Field Emitter Arrays ◽  
Emitter Array ◽  
Field Emitter Array ◽  
Tip Radius

The nanocone-shaped carbon nanotubes field-emitter array (NCNA) is a near-ideal field-emitter array that combines the advantages of geometry and material. In contrast to previous methods of field-emitter array, laser ablation is a low-cost and clean method that does not require any photolithography or wet chemistry. However, nanocone shapes are hard to achieve through laser ablation due to the micrometer-scale focusing spot. Here, we develop an ultraviolet (UV) laser beam patterning technique that is capable of reliably realizing NCNA with a cone-tip radius of ≈300 nm, utilizing optimized beam focusing and unique carbon nanotube–light interaction properties. The patterned array provided smaller turn-on fields (reduced from 2.6 to 1.6 V/μm) in emitters and supported a higher (increased from 10 to 140 mA/cm2) and more stable emission than their unpatterned counterparts. The present technique may be widely applied in the fabrication of high-performance CNTs field-emitter arrays.

Performance Evaluation of a Triangular-Prism-Slit Electrode Pair as an Electro-Conjugate Fluid Jet Generator

2011 ◽  
Author(s):  
Hai-bo Wang ◽  
Joon-wan Kim ◽  
Shinichi Yokota ◽  
Kazuya Edamura
Keyword(s):  
High Performance ◽  
Electrode Array ◽  
Research Field ◽  
Electrode Pair ◽  
Triangular Prism ◽  
Electrode Structure ◽  
Electrode Gap ◽  
Promising Candidate ◽  
Output Pressure ◽  
The Relationship

Electro-conjugate fluid (ECF) is a dielectric and functional fluid, which generates a powerful jet when electrodes inserted into it are subjected to a constant voltage of less than one thousand volts. As one essential research field on ECF, researchers have been conducting the study on electrodes. Several structures, e.g. planar parallel rod-like electrode array, ring-needle electrode pair and triangular-prism-slit (TPS) electrode pair, were proposed. Among them, the TPS electrode structure is often thought as the most promising candidate for future ECF applications thanks to its great merits of combining easy fabrication and relatively high performance. In this paper, in order to evaluate performance of the TPS electrode pair, a novel modular ECF-jet generator capable of independently adjusting alignment and gap of each electrode is designed. By utilizing it, the relationship between output pressure and parameters of the TPS electrode pair, including thickness, slit width, tip angle, electrode gap and alignment, are obtained.

scholarly journals GPU-Based Simulation of Ultrasound Imaging Artifacts for Cryosurgery Training

2016 ◽  
Vol 16 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Robert Keelan ◽  
Kenji Shimada ◽  
Yoed Rabin
Keyword(s):  
Temperature Field ◽  
Ultrasound Imaging ◽  
Ultrasound Image ◽  
Application Programming Interface ◽  
Computational Technique ◽  
Processing Unit ◽  
Computerized Training ◽  
Application Programming ◽  
Imaging Artifacts ◽  
Property Changes

This study presents an efficient computational technique for the simulation of ultrasound imaging artifacts associated with cryosurgery based on nonlinear ray tracing. This study is part of an ongoing effort to develop computerized training tools for cryosurgery, with prostate cryosurgery as a development model. The capability of performing virtual cryosurgical procedures on a variety of test cases is essential for effective surgical training. Simulated ultrasound imaging artifacts include reverberation and reflection of the cryoprobes in the unfrozen tissue, reflections caused by the freezing front, shadowing caused by the frozen region, and tissue property changes in repeated freeze–thaw cycles procedures. The simulated artifacts appear to preserve the key features observed in a clinical setting. This study displays an example of how training may benefit from toggling between the undisturbed ultrasound image, the simulated temperature field, the simulated imaging artifacts, and an augmented hybrid presentation of the temperature field superimposed on the ultrasound image. The proposed method is demonstrated on a graphic processing unit at 100 frames per second, on a mid-range personal workstation, at two orders of magnitude faster than a typical cryoprocedure. This performance is based on computation with C++ accelerated massive parallelism and its interoperability with the DirectX-rendering application programming interface.

Sign in / Sign up

Export Citation Format

Share Document