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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...
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...
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...
Amorphous thin films are used as components of acoustic resonators because they could control temperature coefficient of resonator. Because elastic constants of thin films are often different from those of bulk materials, the direct measurement of sound velocity and temperature coefficient of velocity (TCV) for individual thin films becomes important in designing resonators. Because The TCV of amorphous...
Partial substitution of Al by Sc in AlN wurtzite films leads to a strong enhancement of the piezoelectric properties as long as the wurtzite phase is maintained. This is very promising for improving piezoelectric MEMS devices and enlarging their application range. Nucleation of (0001)-AlScN works particularly well on Pt (111) thin films. However, in some applications, the growth on insulating substrates...
Hydroxyapatite (HAp) is a useful biocompatible material and is used for the surface coating of artificial bone. It has been reported that the oriented HAp promotes rapid recovery of the bone fracture[1], although most of coating HAp layers on the commercial artificial Titanium (Ti) bones are not oriented. As a new coating layer, our group has reported the highly oriented HAp film on Ti substrate fabricated...
Coupling between surface acoustic waves (SAW) and arrays of mechanical resonators has appeared early in SAW history as a potential means to slow down wave propagation through mass-loading, in particular by creating corrugations on the substrate surface. This concept has been revisited over the past few years in the context of locally-resonant phononic crystals where pillars deposited on a homogeneous...
Recently a multilayered structure with a low-velocity layer sandwiched between two high-velocity materials, one of which also works as a supporting substrate and another one as a coat isolating the wave from the influence of undesired external factors, was suggested for application in packageless sensors [1,2]. The thickness of a middle piezoelectric layer must be sufficient to confine the wave within...
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...
Recently, it was shown that heavily doped AlN film possess the high piezoelectricity by Akiyama et al [1]. On the other hand, SAW devices were widely used as filters and sensors. Among them, SAW in ScAlN film is attracting a lot of attention because this SAW devices have high electromechanical coupling coefficient K2. We analyzed the K2 value in Sc0.4Al0.6N was increased by c-axis tilted angle θ becoming...
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...
I.H.P. SAW (Incredible High-Performance SAW) has a novel multi-layered structure to confine SAW energy in substrate surface area, and it shows extremely high quality (Q) factor, low temperature coefficient of frequency (TCF) and improved electromechanical coupling coefficient (K2). This paper introduces its mechanism of the high acoustic Q factor, both theoretically and experimentally, and its applications...
In order to study relaxation characteristics of viscoelasticity of the liquid, a wide frequency sweep in the range of MHz to GHz is desired. We, therefore, report a new type HBAR (High-overtone Bulk Acoustic Resonator: shear mode ScAlN film on AT-cut quartz plate) sensor which makes it possible to operate in a wide frequency range as shown in Fig. 1. When a thickness shear acoustic mode (TSM) resonator...
To understand physiologic state in diseased liver e.g. non-alcoholic steatohepatitis, this study aims to analyze the acoustic impedance (Z) of hepatic cells using a scanning acoustic microscopy (SAM). Ultrasound scattering sources in cells, however, cause the multi-reflection and prevent from analyzing the precious value of Z although it provides the useful information of structure in cells (M. N...
Surface acoustic wave (SAW) devices are widely used as acoustic-electronic components today. The lithium niobate was often used as the substrate of SAW devices for its higher electromechanical coupling coefficient. In some applications like RFID tags and sensors, SAW devices have a long delay line and the energy loss of diffraction is considerable. Phononic crystals (PnC) have properties of band gaps...
Leaky surface acoustic waves (LSAWs) and longitudinal-type LSAWs (LLSAWs) have a number of beneficial characteristics such as a larger electromechanical coupling factor K2 and higher phase velocity than those of Rayleigh-type SAWs. However, LSAWs and LLSAWs have inherent attenuation because they lose energy by continuously radiating bulk waves into the substrate. To solve this problem, the authors...
Recently we reported on fabrication and characterization of a novel type of hybrid resonator in which BAW transforms into SAW due to a periodic pillar pattern of piezoelectric material. This device looks promising thanks to high achievable electromechanical coupling (over 4%) and possibility for application as sensor in harsh environment when using AlScN as piezoelectric. The main feature of the device...
Nanoparticle manipulation has a variety of potential applications, from two-dimensional material fabrication to biomedical engineering. Pattern and transportation of nanoparticles has been receiving increasing attention in recent years. Ultrasound as a mechanical wave has proven to be the most effective in the manipulation of micro-objects in a non-contact and non-invasive fashion. However, due to...
Mobile filters are required to process increasing RF power levels, driven by the need for higher data-rates and improved cell-edge coverage. This results in more demanding filter specifications for loss, rejection, isolation, linearity and reliability, while, at the same time, handset OEMs require smaller filter footprints.
Capacitive Micromachined Ultrasound Transducers (CMUTs) have become a better alternative to traditional piezoelectric transducers because of their better impedance matching characteristic and wider bandwidth. These advantages make CMUTs ideal for medical ultrasound imaging, ultrasonic flow metering, gesture sensing and other airborne applications. However conventional vacuum CMUTs have narrow bandwidth...
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