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Many high-end power machines demand greater bearing performance in terms of running speed, precision, reliability, longevity, noise reduction, etc. An ultrasonic bearing based on Near-Field Acoustic Levitation (NFAL) effect is a kind of emerging noncontact gas bearing. Due to its self-aligning capability, the ultrasonic bearing can steadily run at a high speed under high precision. Actuated by piezoelectric...
The Resolution Enhancement Compression (REC) technique is a coded excitation method developed for improving the axial resolution of ultrasound images. It consists on emitting an amplitude modulated chirp signal that transmits more energy at the frequencies where the ultrasound transducer is less efficient. The focus of this study is to elaborate a new beamforming strategy, which consists of implementing...
Aluminum nitride (AlN) Lamb wave resonators (LWRs) utilizing the lowest symmetric (S0) mode have attracted much interests since they have high frequencies, low motional impedances, and capability of multiple frequencies on a single chip. However, the transverse spurious modes are often strong in AlN LWR, and largely degrade the performance in application, so suppression the transverse mode is highly...
Piezoelectric single crystals (piezocrystals) of lead magnesium niobate-lead titante (PMN-PT) and lead zinc niobate-lead titanate (PZN-PT) have extremely large electromechanical coupling coefficients and exhibit strains of over one percent. The technical significance of these properties to devices is enormous and includes a doubling of bandwidth, decreased package size, and increased resolution. The...
A Love wave sensor with a phononic parylene-C wave guiding layer is proposed to detect the VEGF secreted during the selective platelet activation process, where arrays of a different material (filling material) are fabricated in the parylene-C films. The effects of the structural design parameters (period width and period number) on the electric response of sensors are investigated. As the period...
This paper proposes use of traveling wave type excitation sources for the scattering analysis of RF SAW/BAW devices using the finite element method(FEM). By generating a single mode selectively, scattering behavior at arbitrary edges can be evaluated efficiently in frequency domain. After describing its detailed mechanism, two examples are presented for the use in SAW and BAW models. The results revealed...
Flow velocity estimation is an important feature in ultrasound imaging. However, in conventional color Doppler imaging, only parallel flow components can be estimated, the velocity information is not simultaneously measured throughout the region of interest (ROI) due to sequential firing of the ultrasound beams, and the size of the ROI is limited under frame rate concerns. On the other hand, ultrafast...
Construction of smart city has become a historical trend in the world. The management of underground pipes and the intelligent concrete are the main part of building smart city in China. Compared with the available electronic marker system, SAW-RFID system has shown excellent properties: truly passive, strong penetrating capability, long service-life, sensing and ID integration, and etc. Thus, SAW-RFID...
Cardiac function has traditionally been studied using pressure-volume (PV) loop analysis. PV loops can be used to derive functional indices such as end-systolic pressure volume relationship (ESPVR)—a measure of myocardial contractility, end-diastolic pressure volume relationship (EDPVR) — a measure of myocardial compliance and relaxation time constant (τ) — a measure of left ventricular relaxation...
Arranging microparticles into desired pattern is of particular importance for many applications in the field of micro-electronics-mechanical system, regenerative medicine, tissue engineering and composite fabricating. A variety of techniques for patterning microparticles on the substrate have been developed in recent years based on optic, magnetic and electric field. However, each above mentioned...
The image quality provided by current ultrasound (US) scanners can be increased by extending the effective bandwidth of the US transducers. In 2007, a promising technique, called Resolution Enhancement Compression (REC), was proposed. Combining chirp modulated signals in emission and Modified Wiener Filters (MTF) in reception, REC allows bandwidth enhancement by boosting the energy of the emitted/received...
Controlling cell functions for drug development and therapeutic purposes has been an important method in clinic to treat critical diseases such as cancer and neurodegenerative diseases. Modulation of cancer cells and finding specific mutations in cancer are methods to investigate mechanism of outbreak of cancer. The advancement in molecular biology introduced tools to precisely edit genome of cells...
Intrauterine growth restriction (IUGR) is an anomaly of fetal growth dynamics, which is mainly caused by alterations in the vascular remodeling of utero-placental arteries. With a prevalence of 10% of pregnancies, IUGR remains the leading cause of perinatal mortality. Doppler velocimetry is the common screening tool for IUGR but this imaging modality remains controversial. In this context, we evaluated...
Diamond has the highest sound velocity among all materials and has been applied in high frequency surface acoustic wave (SAW) devices in the gigahertz range. To date, numerous researches have reported that the SAW devices built on a diamond wafer can work in the frequency range from 2 GHz to 10 GHz. S. Fujii et al. reported that the one-port resonator with an interdigital transducer (IDT)/AlN/single...
Myocardial strain imaging has been shown to add significant prognostic and diagnostic value to echocardiography. While the reliability of ultrasound-based strain measurement techniques has improved considerably in terms of regional consistency and inter-reader, inter-vendor agreement; most state-of-the-art strain imaging packages constrain their analyses to individual cardiac cycles. This limitation...
Pathologic microvasculature plays a key role in the leading causes of blindness including diabetic retinopathy, retinal vein occlusions, and macular degeneration. Current treatments, including laser therapy, photodynamic therapy (PDT), and anti-vascular endothelial growth factor (VEGF) therapy, impose significant burdens on patients, their families, and our health system because of frequent administration,...
Tumor growth requires formation of new angiogenic vessels, which differ in their morphology from those of healthy tissue. These vascular abnormalities result in altered blood flow dynamics, which can be assessed by dynamic contrast-enhanced ultrasound (DCE-US). Two distinct approaches are typically employed in DCE-US following an intravenous injection of ultrasound contrast agent: assessment of perfusion...
Cardiovascular disease, including atherosclerosis and critical limb ischemia, affects millions of people worldwide. There is a clinical need to base treatment decisions on quantitative analysis of the plaque composition. However, no reliable clinical methods to quantify the mechanical properties of plaque components and detect plaque vulnerability currently exist, particularly for coronary disease...
Understanding of the propagation of ultrasound through a bubbly medium is a challenging task because of the nonlinear dynamics of the bubbles and their effect on the attenuation and sound speed of the medium. The majority of the studies on this subject apply linear models, which will generate inaccurate results, especially at higher-pressure excitations. These studies have also ignored the effect...
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