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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...
Elastic properties of the ocular tissues are significantly affected by intraocular pressure (IOP) in the eye. For example, the speed of the elastic wave in the cornea dramatically increases with IOP. In our previous studies using ultrasound shear wave imaging we demonstrated that, for the lens, the increase in IOP does not result significant changes in the wave velocity. Compared with ultrasound imaging,...
Based on the least squares method which is arranged to the problem of fitting theoretical to experimental measured variables, such as phase velocities of acoustic waves and/or resonant frequencies, the environment of the minimum sum of squares (SSQ) has been analyzed, similarly to [1]. This is done by forming a “sensitivity matrix” (or Jacobian matrix: derivatives of measured variables with respect...
Shear wave elastography is useful for quantitatively evaluating tissue elasticity by measuring the speed of a shear wave induced within the body by acoustic radiation force. We proposed a pushing-and-tracking sequence, coded push-pulse excitation to increase the signal-to-noise ratio (SNR) of the observed shear wave propagation without increasing measurement time and push-pulse amplitude1). In this...
High-intensity focused ultrasound (HIFU) have been an attractive research topic for some time now. HIFU studies have started with single-element transducers, but using arrays provide the opportunity to scan the focal point electronically. Modular and scalable driving systems that can adapt to custom-made transducer elements to drive these arrays are needed and at the present time there are few such...
The control of acoustic fields in 3-D is vital in many areas of physical acoustics. Recently, a new approach for the generation of complex diffraction limited acoustic fields in 3-D was introduced. This works by calculating a phase hologram designed to generate a desired acoustic field. The output of a simple planar transducer is then mapped onto this phase distribution using a 3-D printed kinoform...
The 30MHz lithium niobate (LiNbO3) ultrasound transducer with a highly focused beam was used to generate gradient force which can pull a single leukemia cell to toward a focus to be a trapping situation. The transducer was sterilized by using 70% ethanol before the experiment. Five leukemia cells before treatment and five cells after treatment by a chemotherapy drug were trapped and measured their...
We present a fully-populated 2D-phased array, capable of emitting directed air-coupled ultrasound at 40 kHz without any grating lobes. In comparison to our previous work [Konetzke et al, IUS 2015], in which we describe a 1D-phased array, we use 3D printing techniques to realize a wave guide structure that fulfills the half-wavelength criteria of 4.3 mm. The key idea is to use the wave-guide structure...
Accurate measurement of acoustic dispersion has important applications in theoretical acoustics, ultrasound tissue characterization, ultrasound measurement systems, etc. Usually, the parameter of interest associated to dispersion is the variation in the propagation velocity as a function of the frequency or the temperature. Nevertheless, this work is focused on the study of the variation in the propagation...
Forward-looking intravascular ultrasound (FL-IVUS) transducers are needed to image complex lesions in the coronary arteries, such as chronic total occlusions (CTOs). To achieve 2D and 3D FL-IVUS imaging, transducer arrays can be integrated at the tip of the catheter. However, connecting the elements is challenging due to the limited space available. In this work, we present a FL-IVUS matrix transducer...
Oil has been used in many fields, such as transportation systems and machine tools. Performances of those depend on oil quality. However, quality is normally checked by visual inspection. Therefore, it is required to develop a sensor for monitoring oil quality to measure online and real time. A shear horizontal surface acoustic wave (SH-SAW) sensor can detect liquid properties. In this paper, particles...
Subharmonic aided pressure estimation (SHAPE) is based on the inverse relationship between the subharmonic amplitude of contrast microbubbles and the ambient pressure. A noninvasive ultrasound based pressure estimation procedure would be a major development in the diagnosis of portal hypertension and less invasive than the current hepatic venous pressure gradient (HVPG) measurement. The hypothesis...
This article is focused on the characterization of the lack of homogeneity in the dispersive acoustic properties of polymeric materials used in industrial pipes. Usually, the parameter of interest associated to dispersion is the variation in the propagation velocity as a function of the frequency or the temperature. Nevertheless, this paper, studies the variation in the propagation velocity, as a...
In previous work, the advantage of using super-harmonic contrast imaging to visualize the microvasculature in tumors and organs has been demonstrated [1]. This was performed using dual frequency (DF) probes consisting of a high frequency single element transducer from a motorized probe concentric with a low frequency ring [2]. However, mechanically scanned systems have limitations, including single...
The noncontact acoustic inspection method has been studied using a laser Doppler vibrometer (LDV) of high sensitivity and a sound source which can generate big sound pressure at a long distance. However, the inspection at the long distance over 10 m was carried out only with the concrete test object. Therefore, for an actual concrete bridge in Japan, the long distance measurement experiment over 30...
Non-alcoholic fatty liver disease (NAFLD) is a major health concern due to the increasing obesity epidemic and it has the risk to progress to liver fibrosis, cirrhosis and hepatocellular carcinoma. It is important to assess the severity of hepatic fibrosis for the risk-stratified management of patients with NAFLD. Ultrasound elastography is a new technique for evaluation of liver fibrosis and it has...
In this study the acoustic properties of small animal soft tissue was measured over the frequency range 12–32 MHz. Measurements were taken at 6 minutes after euthanasia. Using phosphate buffered saline (PBS) at 37°C as the reference medium a high frequency ultrasound scanner Vevo 770® was employed to measure the acoustical properties. The mean SoS measured from brain, liver and kidney was found to...
Ferroelectric polymers like polyvinylidenefluoride (PVDF) and its copolymer with trifluoroethylene [P(VDF-TrFE)] are widely used in sensor and transducer applications. Good acoustic match to many materials (e.g. water, polymers, and human tissue) and high chemical stability make these materials suitable for ultrasonic applications, especially in the high frequency end (20 MHz-1 GHz). The current work...
The biaxial driving technique enhances the mechanical response of a piezoelectric actuator by dephasing two orthogonal electrical fields to the propagation and lateral electrodes. This paper presents results on the relationship between the electrical response and the phase at which the maximum acoustic efficiency was reached on a single element biaxially driven ultrasound transducer. Eight air-backed...
This paper proposes a vector measurement method of nonlinear response generated in SAW/BAW devices. A cross domain analyzer, a spectrum analyzer with to input channels, is used to detect vector amplitude of very weak nonlinear signals. Second and third harmonics and intermodulation distortion signals were measured, and validity of the measurement was demonstrated.
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