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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...
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...
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...
Quantum Spin Hall Effects(QSHE) underpins most of the design in topological insulators. The intrinsic spin-0 of the phononics, yet, continue to be the main barrier in designing acoustic topological insulators. Previous research proposed a solution using external fields such as clockwise and counter-clockwise circulating fluids to create artificial acoustic spin-1/2 states. Most recently, several papers...
The acoustic microstreaming originating from microbubbles' linear oscillations can be used as a potential cell sonoporation tool for drug delivery and gene transfection. However, this bubble-based method suffers from bubble instability, non-uniform size, unreliable performance, and inconvenient trapping. In order to overcome the above drawbacks, in this study, we proposed a massive drug delivery method...
The concept of the band structure is central to the field of phononic crystals. Indeed, capturing the dispersion of Bloch waves — the eigenmodes of propagation in periodic media — gives invaluable information on allowed propagation modes, their phase and group velocities, local resonances, and band gaps. Band structures are usually obtained by solving an eigenvalue problem defined on a closed and...
This article investigates a flow-free, pseudospin-based acoustic topological insulator. Zone folding, a strategy originated from photonic crystal, is used to form double Dirac cones in phononic crystal. The lattice symmetry of the phononic crystal is broken by tuning the size of the center “atom” of the unit cell in order to open the nontrivial topological gap. Robust sound one-way propagation is...
High channel count, large area ultrasound arrays at fine pitch require close integration of transducer elements and ASIC electronics. Composites of single crystal material and non-conducting epoxy filler can be used to increase bandwidth. Direct bonding of the composite to the ASIC leads to acoustic mismatch and excessive ringing. A collimated connection block (i.e. an interposer) between the array...
With its thickness decreasing down to 60 μm, the (K0.45Na0.55)0.96Li0.04NbO3 (KNLN) single crystals maintains superior piezoelectric constant (d33 = 675 pC N−1). In combination with a 200 μm core multimode fiber, the successful fabrication of a tiny intravascular photoacoustic probe with a 1 mm outside diameter is achieved. The intravascular photoacoustic imaging of the atherosclerotic lesion of a...
Clinically used Intravascular Ultrasound (IVUS) imaging majorly operates in the 20∼40MHz range, providing resolution on the order of 100μm. Recent reports showed the potential of higher frequency (60–80MHz) of IVUS improving resolution to the level of 30–60μm, but still inferior to the resolution of OCT (10μm). Whether increasing the working frequency a step further could make IVUS comparable to OCT?...
Nanoparticles have been required in the fields such as medicine, foods and electronic materials. By re-crystallization process, nanoparticles can be formed by quenching a solution. We have generated mono-disperse droplets by using a torsional bolt-clamped Langevin-type transducer and a micropore plate to form fine nanoparticles by quenching the droplets.
In this paper, we describe process development and initial results for a tileable 2D array module for implementation of large area arrays. The module is based on a 1–3 composite of single crystal PIN-PMN-PT transducer material which benefits from improved electromechanical coupling coefficient k33' and increased Curie temperature. The backing for the array consists of a novel 3D printed acrylic frame...
Piezoelectric materials are at the heart of electromechanical devices, such as medical imaging transducer, high intensity focused ultrasound (HIFU), industrial nondestructive evaluation (NDE) and piezoelectric sensors, to name a few. In this presentation, the advantages and disadvantages of piezoelectric materials are discussed based on the requirements (figure of merit) of various applications, with...
Intravascular photoacoustic (IVPA) imaging, which combines the advantages of high ultrasonic resolution and strong optical absorption contrast, seems to be an alternative method to detect lipid pool and atherosclerotic lesion. A highly sensitive miniaturized ultrasound transducer is required for receiving of intravascular photoacoustic signals. As the core part of the transducer, lead-based piezoelectric...
The behavior of vibrating crystal plates under the action of external forces was studied. The plates were respectively subjected to diametrical compression force and bending force in different configurations: (a) a clamped cantilever, (b) a cantilever with displaced knife edges, and (c) a dual support mounting with displaced knife edge applied midway between. Finite element models were developed using...
Since the beginning of using piezoelectric single crystals for highly-precise microacoustic components rigorous knowledge of material constant (MC) sets was an indispensable requirement for mastering the subject. The sets have to be both accurate and complete. Accuracy is important for acceptable agreement between device simulation and experimental reality, completeness preferentially plays a role...
Diamond is known to have the highest sound velocity of all materials, and therefore, has been applied to high frequency surface acoustic wave (SAW) devices in the gigahertz range. Our earlier research has shown much potential for diamond SAW resonators and filters on single crystal substrates at frequencies above 3 GHz. However, single crystal diamond wafers of only up to two-inch in diameter have...
Phononic crystals have attracted intensive research interest for decades since the early 1990s. They exhibit a spatially periodic feature regarding the distribution of physical properties, geometry, boundary conditions, or/and external stimuli, making their wave spectrum quite different from the conventional continuous one, usually with frequency band gaps where waves cannot propagate through them...
As one of the most important and well established tools, ultrasound imaging provides noninvasive valuable diagnostic information, especially in the form of cross-sectional images of soft tissues. High frequencies are used directly to enable high resolution imaging to be of clinical benefit. As a result, high-frequency ultrasonic transducers with better resolution are needed. The difficulty of a high...
The creating different kinds of the phononic crystals and acoustic metamaterials, which has advanced ultrasound properties, have generated considerable recent research interest. The new kind acoustic materials, allows to studying the new effects of the ultrasound interaction and developing different types of the surface acoustic wave (SAW) devices for electronic industry. We represented the possibilities...
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