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It is commonly known that a merry-go-round can be rotated even by a child going along its edge. The angular momentum of the whole system should be equal to zero so that the movement of the child results in a merry-go-round movement in opposite direction. Here we show experimentally that a macroscopic cylindrical solid can be rotated due to the existence of the momentum of surface acoustic wave propagating...
We have been studying experimental methods using cultured cardiomyocytes to evaluate the effect of short-pulsed ultrasound for generating disruption in pulsation such as premature contractions. In this study, we focused on the effect of ultrasound pulses with longer duration for a basic study on the safety of acoustic radiation force impulse (ARFI) imaging. Cardiomyocytes isolated from neonatal rats...
The aim of this investigation is to determine if the heterogeneous sonoporation depends on the microbubble size. Using a customized ultrasound exposure and observation setup, we observed sonoporation dynamics at the single-cell level and quantified exogenous molecular uptake levels to evaluate the degree of sonoporation. The non-uniform size distribution of SonoVue microbubbles themselves allowed...
Recently immunotherapy using therapeutic cells has attracted attention. Because the cells injected in human body disperse through the blood stream, there is a problem that small amount reaches to the diseased area. So we intend for in vivo cell delivery system, which is realized by attracting nanobubbles on the surface of cells to reduce its density for dynamic control of cells under ultrasound emission...
Acoustic radiation force has many applications. One of the related technologies is the ability to noninvasively expel stones from the kidney. To optimize the procedure it is important to develop theoretical approaches that can provide rapid calculations of the radiation force depending in stone size and elastic properties, together with ultrasound beam diameter, intensity, and frequency. We hypothesize...
Influence of mechanical force applied parallel to the wedge of an edge (D16 aluminum alloy) on velocity, absorption of acoustic wedge waves and specifics of second harmonic generation is studied experimentally in the paper.
VisR ultrasound is an acoustic radiation force (ARF)-based imaging method that fits induced displacements to a 1D mass-spring-damper (MSD) model to estimate the ratio of viscous to elastic moduli, τ, in viscoelastic materials. A source of error in VisR τ estimation is complex and interrelated 3D system inertia. We hypothesize that error due to system inertia may be reduced by minimizing the volumetric...
The paper presents modelling and finite element simulation of a surface acoustic wave (SAW) motor based on dual friction-drive (DFD). The DFD SAW motor comprises of a flat cuboid slider tightly held between two identical piezoelectric stators typically made of lithium niobate facing each other, each stator having an interdigital transducer (IDT) fabricated on its either side. A sinusoidal excitation...
Our work deals with the study of the dynamic characteristics of a single circular CMUT transducer under squeeze film damping effect. A simplified analytical approach is developed for parallel plate approximation for the electromechanical behavior and the squeeze film damping. Analytically calculated results demonstrates, that trends of resonant frequency with bias voltage are defined by the ratio...
In this paper, we designed and simulated a multilayer planar resonator with target frequency of 2.5 MHz which is created over a row/column-addressed 2D CMUT array. We have shown through finite element modeling and simulations that a particle can be trapped and manipulated both in lateral and axial directions inside the fluid channel by activating CMUT elements; And calculated acoustic radiation force...
This paper investigates the dynamic acoustic sorting method from a theoretical perspective. Analytical equations of motion and numerical simulations have been used to optimize parameters for sorting various particle mixtures. The effect of changes in field parameters as frequency or voltage on efficient sorting has been investigated. Experiments have been carried out to verify theoretical findings.
This research quantitatively estimates stiffness by measuring the time-to-peak displacement directly along the acoustic radiation force (ARF) axis in contrast to shear wave elasticity imaging (SWEI) that measures shear wave velocity at lateral locations. We have shown previously in simulation results that an advanced displacement estimator reduces variability in the final stiffness estimate. Here,...
Electrostatic nonlinearity limits the use of Capacitive Micromachined Ultrasonic Transducers (CMUTs) in nonlinear ultrasound modalities, such as contrast and tissue harmonic imaging. In this paper, we experimentally investigate the performance of a linearization method based on the appli-cation of pre-distorted analog excitation signals whose spectral content compensates the harmonic distortion introduced...
Automated ultrasound breast imaging could overcome most of the limitations of conventional echography, ensuring repeatability and better patient follow-up. Several research groups have included multi-modality in these kind of systems, obtaining velocity and attenuation maps. This work addresses the implementation of the Acoustic Radiation Force Imaging (ARFI) technique in a Full Angle Spatial Compounding...
Capacitive Micromachined Ultrasonic Transducer (CMUT) is a new type of ultrasound wave generator and detector. Analytical method is intuitive to understand the mechanism and physical effects through modeling of CMUT. To optimize the design procedures of CMUT membrane undergoing large deflection, a new analytical model with the consideration of the lateral force using Von Kármán equations is proposed...
Mechanisms for non-invasive target drug delivery using microbubbles and ultrasound have attracted growing interest. Microbubbles can be loaded with a therapeutic payload and tracked via ultrasound imaging to selectively release their payload at ultrasound-targeted locations. In this study, an ultrasonic trapping method is proposed for simultaneously imaging and controlling the location of microbubbles...
Duchenne muscular dystrophy (DMD) is a genetic disorder that causes progressive muscle degeneration involving necrosis and inflammation, with subsequent replacement of muscle fibers by fibrosis and fatty tissue. These compositional changes underlie mechanical property alterations in affected muscles, which may be assessed using Viscoelastic Response (VisR) ultrasound. We hypothesize that VisR will...
The ability to manipulate microparticles or nanoparticles precisely is important for the development of microsystem. Acoustic tweezers are excellent tools for manipulating particles with size approaching or slightly smaller than wavelength. However, manipulation of microparticles with much smaller size requires stronger acoustic confinement and higher intensities than can be provided by these diffraction-limited...
This paper presents the numerical determination of the acoustic radiation force that acts on a sphere in an acoustic levitation device formed by a 25 kHz ultrasonic transducer and a concave reflector. The acoustic radiation force is determined by two numerical models based on the Finite Element Method. In the first model, the acoustic pressure and velocity distributions are calculated numerically...
Ultrasound elasticity imaging (UEI) is a noninvasive method for characterizing mechanical properties of soft tissue. This technique potentially provides important feedback for making treatment decision for advanced tendinopathies, such as posterior tibial tendon dysfunction (PTTD). Highly variable lateral strain along the length of the tendon has been observed during human experiments. To better understand...
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