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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...
“Acoustic angiography” is a super-harmonic contrast imaging technique, which is based on the fact that when excited with a moderate acoustic pressure near their resonance (2–4 MHz; around MI of 0.5–0.7) ultrasound contrast agents produce broadband content which extends well past 15 MHz. By detecting the higher order harmonic energy while transmitting at a low fundamental frequency, exquisite resolution...
Acoustic delay lines based on Al0.85Sc0.15N thin film hybrid transducers were investigated by finite element modeling. It was found that an acoustic impedance matching between transducer and non-piezoelectric substrate material plays a crucial role to efficiently excite a traveling surface acoustic wave (SAW) through the BAW piston motion. Test devices based on the 2.5 um thick Al0.85Sc0.15N piezoelectric...
For new-generation thermal power plants, off-line non-destructive testing is not sufficient and long-term monitoring at high temperature is desired. In the previous study, ultrasonic transducers made by CaBi4Ti4O15 (CBT)/Pb(Zr, Ti)O3 (PZT) were investigated and maximum operation temperature was estimated as ∼600°C. Since operation temperature of new-generation thermal power plant will be ∼700°C, it...
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...
Enegy harvesting from surrounding electromagnetic wave have attracted much attention in recent years. Low RF-DC conversion efficiency in the rectenna due to a weak power of electromagnetic wave is a problem. We here report the new type of polarization inverted FBAR transformer for RF amplification in the rectenna. c-Axis zig-zag polarization inverted 12 layer ScAlN was fabricated by glancing sputtering...
Film bulk acoustic wave resonator (FBAR) filters are promising for the mobile communication devices. Frequency switchable filters are suitable for selecting the vacant frequency bands. Usual polarity unidirectional single layer resonator excites fundamental mode whereas polarity inverted double layer resonator excites second mode. In this study, we considered that polarity inverted structure is easily...
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...
Multilayered structures with LT plates bonded to silicon or glass substrates via AlN, isotropic SiO2 or their combinations, were theoretically investigated as potential materials for resonators with high Q-factors required for the 5th generation of mobile communication systems. Characteristics of SH-waves propagating under Al grating in such structures, including electromechanical coupling and propagation...
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...
We explore the frequency dependence of piezoceramic disc transducers bonded to plates. For some transducer dimensions, the frequency response shows a sharp peak. This behavior is inconsistent with the use of short pulses or broadband chirps for flaw localization. We use finite element simulation to show that the highly resonant behavior is caused by a high-strain region immediately beneath the transducer...
Flexible ultrasonic transducers have been demanded growing for non-destructive testing (NDT). Pb(Zr, Ti)O3/Pb(Zr, Ti)O3(PZT/PZT) sol-gel composite ultrasonic transducers made by spray coating technique have flexibility. However, in this method, it required operator's experience and not suitable for mass production due to film quality individual difference. Therefore, automatic spray coating is desired...
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