Michio Kadota

Bio: Michio Kadota is an academic researcher from Tohoku University. The author has contributed to research in topics: Surface acoustic wave & Resonator. The author has an hindex of 30, co-authored 262 publications receiving 3419 citations. Previous affiliations of Michio Kadota include Murata Manufacturing.

Surface wave device

Abstract: A surface acoustic wave device which is a surface acoustic wave resonator utilizing an SH-type surface wave, wherein a resin layer made of a resin material in the form of gel or having a Shore hardness of not more than 30 is formed so as to coat at least an interdigital transducer formed on the upper surface of a piezoelectric substrate.

Development of Substrate Structures and Processes for Practical Applications of Various Surface Acoustic Wave Devices

Abstract: The author and coengineers have developed, put to practical use, mass-produced, and commercialized various surface acoustic wave (SAW) devices. Their success depended largely on the development of SAW substrate materials, SAW device structures, and the processes of producing with the cooperation of many engineers. The author reports the development and practical applications of several SAW devices: (1) ZnO/glass structure SAW filters for video intermediate frequency (VIF) for televisions (TVs) or video cassette recorders (VCRs), (2) small resonators and filters using Bleustein-Gulyaev-Shimizu (BGS) wave's edge reflection on ceramic substrates, (3) small filters using shear horizontal leaky SAWs on heavy-density-metal electrode/quartz structures, (4) ZnO/quartz structure SAW filters, and (5) SAW duplexers with excellent temperature characteristics for personal communication services (PCSs) in the US.

High-frequency lamb wave device composed of MEMS structure using LiNbO 3 thin film and air gap

Abstract: High-frequency devices operating at 3 GHz or higher are required, for instance, for future 4th generation mobile phone systems in Japan. Using a substrate with a high acoustic velocity is one method to realize a high-frequency acoustic or elastic device. A Lamb wave has a high velocity when the substrate thickness is thin. To realize a high-frequency device operating at 3 GHz or higher using a Lamb wave, a very thin (less than 0.5 μm thick) single-crystal plate must be used. It is difficult to fabricate such a very thin single crystal plate. The authors have attempted to use a c-axis orientated epitaxial LiNbO3 thin film deposited by a chemical vapor deposition system (CVD) instead of using a thin LiNbO3 single crystal plate. Lamb wave resonators composed of a interdigital transducer (IDT)/the LiNbO3 film/air gap/base substrate structure like micro-electromechanical system (MEMS) transducers were fabricated. These resonators have shown a high frequency of 4.5 and 6.3 GHz, which correspond to very high acoustic velocities of 14 000 and 12 500 m/s, respectively, have excellent characteristics such as a ratio of resonant and antiresonant impedance of 52 and 38 dB and a wide band of 7.2% and 3.7%, respectively, and do not have spurious responses caused by the 0th modes of shear horizontal (SH0) and symmetric (S0) modes.

Wideband acoustic wave resonators composed of hetero acoustic layer structure

Abstract: A plate wave resonator illustrated in Fig. 1 (a) has attractive features such as large electromechanical coupling factor (k2) and high phase velocity. For example, 0-th shear horizontal (SH0) mode plate wave has k2 larger than 50% in a LiNbO3 (LN) plate thinner than 0.1λ around an Euler angle of (0o, 120o, 0o).1) In our previous study,2, 3) an SH0 mode plate wave resonator exhibited a large bandwidth (BW) of 22%. Ladder filters for a TV white space cognitive radio4) were also prototyped using the plate wave resonators, and extremely wide passband at 6 dB attenuation of 41 to 51%, which was enough to fully cover digital TV band in Japan, USA and EU, was obtained.3) On the other hand, the ultra-thin LN plate thinner than 0.1λ was more fragile than expected, which must be addressed for practical application. To solve the problem, a lot of attentions are recently paid to a new type of acoustic wave device, “Hetero Acoustic Layer (HAL) SAW device,” which has a single crystal piezoelectric thin plate solidly supported with a substrate, as shown in Fig. 1 (b).5-10) Our previous papers reported SH type LN HAL SAW resonators with a high velocity of 6,000 m/s or a wideband of 20%, but the measured impedance ratio was smaller than expected.6,8) In this study, we achieved a very high impedance ratio of 83 dB using a 3.5 μm thick LN plate. This paper reports the finite element method (FEM) simulation, fabrication and characterization of the HAL SAW resonator.

Small surface acoustic wave duplexer for wide-band code-division multiple access full-band system having good temperature characteristics

Abstract: A small surface acoustic wave (SAW) duplexer for a wide-band code-division multiple access (W-CDMA) system with a good temperature coefficient of frequency (TCF) has been required. However, the conventional SAW duplexer for W-CDMA using Al electrode/50–70° YX-LiNbO3 is large (3.8×3.8 mm2) and its TCF is not good (-80 ppm/°C). When a SiO2 film is deposited on this substrate to improve its TCF, good frequency characteristics cannot be realized. Thus, by using a new structure such as a flattened SiO2 film/Cu electrode/substrate structure to improve the TCF, YX-LiNbO3 substrate to obtain a large coupling factor, and flip-chip bonding to miniaturize the duplexer, a small (3×2.5 mm2) SAW duplexer having a low insertion loss and a good TCF has been realized for the first time.

A comprehensive review of zno materials and devices

Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

Apparatus and methods for treatment of morbid obesity

Abstract: Apparatus and methods are described for treatment of morbid obesity using minimally invasive techniques. The apparatus includes a system of components that may be used separately or in combination for effectively reducing stomach volume, bypassing a portion of the stomach and/or small intestines, reducing nutrient absorption in the stomach and/or small intestines and/or depositing minimally or undigested food farther than normal into the intestines, thereby stimulating intestinal responses. The components described include an artificial stoma device, a gastric sleeve device, an intestinal sleeve device, a combined gastrointestinal sleeve device and permanent and detachable attachment systems. Also described are devices for delivering and deploying the components of the system.

Method for forming ZnO film, method for forming ZnO semiconductor layer, method for fabricating semiconductor device, and semiconductor device

Abstract: A ZnO buffer layer having an electric conductivity of 1×10−9 S/cm or lower or alternatively a ZnO buffer layer having a diffraction peak of a crystal face other than (002) and (004) in X-ray diffraction is formed on a substrate by sputtering. A ZnO semiconductor layer is formed on the ZnO buffer layer. The ZnO semiconductor layer is formed under the condition that the flow rate ratio of an oxygen gas in a sputtering gas is lower than that in the formation of the ZnO buffer layer.

Microscale acoustofluidics: Microfluidics driven via acoustics and ultrasonics

Abstract: This article reviews acoustic microfiuidics: the use of acoustic fields, principally ultrasonics, for application in microfiuidics. Although acoustics is a classical field, its promising, and indeed perplexing, capabilities in powerfully manipulating both fluids and particles within those fluids on the microscale to nanoscale has revived interest in it. The bewildering state of the literature and ample jargon from decades of research is reorganized and presented in the context of models derived from first principles. This hopefully will make the area accessible for researchers with experience in materials science, fluid mechanics, or dynamics. The abundance of interesting phenomena arising from nonlinear interactions in ultrasound that easily appear at these small scales is considered, especially in surface acoustic wave devices that are simple to fabricate with planar lithography techniques common in microfluidics, along with the many applications in microfluidics and nanofluidics that appear through the literature.

Devices and methods for treating morbid obesity

Abstract: The present invention provides devices and methods for attachment of an implanted device, such as an artificial stoma device (202), a gastrointestinal sleeve device (200, 258, 278, 428, 458, 560) or an attachment cuff (214, 550, 570), within a patient's digestive tract for treatment of obesity. Special surgical fasteners (100, 130, 222, 240, 250, 276, 530, 542) provide a lasting and durable attachment to the gastrointestinal tissue without causing excessive pressure that could result in tissue erosion and detachment of the implanted device. Fastener delivery devices (150) that facilitate peroral placement and deployment of fasteners (100, 130, 222, 240, 250, 276, 530, 542) and secondary devices are also provided. Also described are implantable devices and attachment means (230, 234) that avoid causing excessive pressure within the tissue by having compliance that is compatible with the gastrointestinal tissues where it is attached.