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Flow cytometer plays a key role in cell sorting and analysis. For a higher detection precision, sheath flow is adopted to avoid the turbulent or vortex effect when the cell flowing through a capillary tube during the cell counting in many commercial cytometers. This method works well when the low flow velocity is relatively low. However, in order to have a higher analysis efficiency for clinical laboratories,...
Ultrasonic guided wave inspection has been in use for more than two decades. Its main advantage is that large sections of pipes can rapidly be screened. However, large area coverage comes at the cost of reduced resolution. Higher resolution can be achieved at higher frequencies-thickness products (> 300 kHz∗mm in steel), where more wave modes are excited; however, this makes the received signals...
Laser Induced Phased Arrays (LIPAs) use post processing to focus and steer the generated ultrasonic beam, synthesizing a phased array. Their principle is based on laser ultrasonics where lasers are used to generate and detect ultrasound. The technique is broadband, non-contact, and couplant free, making LIPAs suitable for large stand-off distances, inspection of components of complex geometries and...
A row-column-addressed (RCA) 2-D array can be interpreted as two orthogonal 1-D arrays. Since the transmit and receive 1-D arrays are orthogonal to each other, only one-way focusing is possible in each transmit or receive plane. By transmitting with row elements and receiving the echoes through column elements, a rectilinear volume in front of the array can be beamformed. This study suggests to use...
In recent years, focusing an ultrasound beam on a subwavelength scale, i.e. beyond the diffraction limit, has attracted much attention. Under this circumstances, the beam is referred to as a superfocused beam. Focusing beyond the diffraction limit may substantially improve the resolution of ultrasound imaging systems, underwater sonar, and acoustic microscopy. Also, it may further enhance particle...
The primary aim of this work was to develop and study the potential of Capacitive Micro-machined Ultrasound Transducers (CMUTs) for dual-mode ultrasound therapy and imaging. This was investigated in the context of Ultrasound-guided High Intensity Focused Ultrasound (USgHIFU) designed for endocavitary HIFU tissue ablation of the prostate gland. The hypothesis is that this CMUT design could offer potential...
Imaging using the total focusing method (TFM) is a popular tool in nondestructive evaluation and it becomes a standard. From full matrix capture, this method consists in focusing at each point of a defined reconstruction zone. It is generally more efficient than conventional phased array focusing that can focus at only a few points. Despite the good quality of TFM images, TFM suffers from a lack of...
We have designed and implemented an ultrasonic imaging research platform that performs all signal processing including beamforming, using software on a GPU. Software-based approach on the GPU is expected to reduce the hardware complexity and offer the advantages of flexibility and rapid implementation even if there is any future change in the requirements for ultrasound imaging applications. An operating...
Acoustic lenses, concentrating the acoustic energy into a specific area, have attracted interest due to their broad applications in various domains, such as biomedical imaging, nondestructive testing, etc. For waterborne sound, conventional silicone materials are fabricated with concave shape for focusing wave. However, it is not flexible to design a concave lens than a flat lens to manipulate acoustic...
Recently, it has been developed a sound source capable of irradiating aerial ultrasonic waves of very high intensity, and researches on applied technologies utilizing the ultrasonic power have been actively conducted. In these applied technologies, it is necessary to irradiate sound waves to the object under optimum conditions. However, this technique has a problem that optimum sound wave irradiation...
Intravascular ultrasound (IVUS) has frequently been used by the cardiologist to diagnose atherosclerosis and guide the interventional procedures. IVUS has gained widely clinical acceptance over the past twenty years because of its superior capability to assess plaque burden and monitor artery remodeling, which also makes it as the irreplaceable image modality for most innovative multimodality intravascular...
Networks of miniaturized implantable medical devices (IMDs) capable of operating deep in the body are crucial for many novel diagnostic and therapeutic applications. An external portable base station to power, coordinate, and communicate with IMDs can enable these networks. Ultrasonic (US) wireless power transfer is utilized to shrink device dimensions, raise available power, and increase operation...
High frequency transducers (>15 MHz) have been widely used in small animal ultrasound, ophthalmic ultrasound, skin ultrasound and intravascular ultrasound et. al. The images obtained by a plane transducer have lower resolution and sensitivity compared with a focusing one. It is usually hard to make the focusing transducer with micro size, short focal length and high frequency. For solving these...
Synthetic aperture focusing based on planar waves also known as coherent plane wave compounding (CPWC) was introduced to reduce the diffraction spreading effect of ultrasound at depths (Song et al. US Patent 6736780, 2004). CPWC has been widely used in shear wave elasticity imaging due to its capability of ultrafast frame rate (Montaldo, et al. IEEE TUFFC, vol. 56, 2009). However, CPWC based on unfocused...
Ultrasound therapy requires focusing high pressures in confined focal spots, to ablate tissues. For organs like the heart, the treatment is challenging, as the US beam must cross the ribs. Part of the energy is reflected by the bones, leading to potential injuries at tissue — bone interface and a pressure drop on target. With usual therapy devices — large transducers on spherical shells — an adaptive...
The Synthetic Aperture Focusing Technique (SAFT) is a reconstruction strategy for ultrasonic non-destructive inspection, which allows the focusing of multiple measurements by superposition. Here, it is applied for the inspection of heavy plates, where a plate is scanned with a fast feed rate by an ultrasonic sensor and a decision about material quality (inclusions, holes, cracks, etc.) has to be made...
A row-column-addressed (RCA) 2-D array can be interpreted as two orthogonal 1-D arrays. By transmitting with row elements and receiving the echoes through column elements or vice versa, a rectilinear volume in front of the array can be beamformed. Since the transmit and receive 1-D arrays are orthogonal to each other, only one-way focusing is possible in each transmit or receive plane. For applications,...
Laser Induced Phased Arrays (LIPAs) use post processing to focus and steer the laser generated and detected ultrasonic beam, synthesizing a phased array. The technique is broadband, non-contact, and couplant free, making LIPAs suitable for large stand-off distances, inspection of components of complex geometries and hazardous environments. This paper presents LIPAs synthesized by capturing the Full...
In this work, we present experimental results on subwavelength focusing of an ultrasound beam by a polymer ball-shaped lens (Rexolite) immersed in water at room temperature. The superfocusing phenomenon occurs in the shadow region of the ball lens in the nearfield. The ball lens with radius 12.2 mm yields a focused beam with a 14.4 dB-intensity gain, a subwavelength focal spot with the full width...
Flow cytometer plays an important role in cell sorting and analysis. Traditional flow cytometers adopt hydrodynamic focusing method which works well when the low flow velocity is relatively low. However, in order to have a higher analysis efficiency for clinical laboratories, a higher flow velocity is preferred, which sometimes will lead to cells siltation when using sheath flow. In this paper, an...
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