Highly resistive soft magnetic (CoFeB)-(SiO₂) films were deposited on glass substrates and polyimide substrates.The frequency dependence of the permeability of the films was investigated in the range of a few GHz. The films exhibited flat frequency profiles with constant μ_r' up to 800 MHz, and high resonance frequencies of 1.1-1.8 GHz. The thickness dependence of the reciprocal of the loss factor tan δ(μ_r'/μ_r") was compared at 1 GHz for the films deposited on glass substrates. Films with a thickness of 0.1 μm exhibited a low loss factor over 5, which indicated good potential for application in a 1 GHz-inductor.

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This paper presents a hard-magnetic-material-type rotary device whose axis of rotation is parallel to the direction of the exciting magnetic field. Permanent magnets and some silicon steel sheets were used to obtain the radial components of the field strength. Because the principle of movement is similar to that of synchronous motors, the starting torque was still small and the moving direction was also unstable. To solve these problems, the permanent magnets distributed on the rotor surface were inclined to the fixed rotation direction. In addition, triangular silicon steel sheets were used instead of the previous rectangular ones. And still more, we gave the other two permanent magnets to the axis of rotation. Measurement results show that the improved device has a starting torque in the fixed direction of motion and it's starting torque is larger than the previous one.

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Soft magnetic (CoFeB)-(SiO₂) films with highly electrical resistivity were deposited on glass substrates and hard-cured polyimide substrates by synchronous dual-rf magnetron sputtering. Frequency dependence of the permeability of the films was investigated. The films on both substrates exhibited highly resistive soft magnetic properties and a flat frequency profile with constant μ_r' over 800 MHz and a high resonance frequency of 1.5 to 1.8 GHz. The reciprocal of the loss factor tan δ (μ_r'/μ_r") at 400 MHz was about 30 for the film on a glass substrate.
Films deposited on hard-cured polyimide were applied to a 1-GHz drive frequency inductor. Inductance of the inductor increased by about 20% compared with that of the inductor without these films.
It was concluded that the (CoFeB)-(SiO₂) films exhibited superior low loss characteristics in the range of 10 MHz to lGHz.

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We microfabricated magnetic thin-film inductors for use as rf front-end receiver impedance matchers in 1-GHz-drive mobile communication handsets. This is the first practical application of soft magnetic films in the 1-GHz range. Fe-Al-O high-resistivity thin films were used for the inductors. The purpose of this paper is to demonstrate a method of reducing the loss of magnetic thin films. Thin Cr films were used as underlayers for the Fe-Al-O films in order to solve the problem. We slit the magnetic thin films in order to reduce eddy current losses. The resistance of the inductor decreased by 40% at 1 GHz. A quality factor of Q = 7.4 was achieved by using a Cr underlayer and slits at 1 GHz.

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To move the magnetic micro-machine to an objective area, it is required to control its running direction. It was demonstrated that swimming direction of the spiral-type magnetic micro-machine could be controlled by changing the direction of the rotation plane of the external rotational field. The swimming direction of the machine turned to the direction of perpendicular to the rotation plane. The radius of the bend depended on the kinematic viscosity of the fluid and on the frequency of the external rotational field.

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Issues related to magnetic shielding effects are discussed for inner-coil-type thin-film inductors with closed magnetic circuits. The relationship between magnetic shielding effects, mutual inductance, and proximity effects is investigated by using the finite integral equation method. The results show that obvious shielding effects occur in the inductors and that the mutual inductance is not influenced by the shielding effects.

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The swimming properties of a magnetic micro-machine with a spiral structure were examined experimentally and theoretically under very low Reynolds number conditions. It was demonstrated that the micro-machine could swim in a highly viscous fluid with a Reynolds number of 10^-7. This result suggests that the micro-machine has a great potential for medical applications. It was found that the optimum blade shape of the micro-machine varied with the Reynolds number condition.

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本稿では、パラトグラフィーおよびリンゴグラフィーという静的な生理音声学的方法を用いて、日本語のラ行子音を観察した。この方法は、塗布剤がついた口蓋あるいは舌で調音位置を判断するものであるが、/da/と/ra/の違いについては、接触面積の差によって破裂音かはじき音かという調音様式を判断できると想定した。結果として、両者の区別は接触面積が相対的に小さい方がはじき音であることが確認できた。他に/ra/が側面音になる者、/da/の調音の際に舌背全体が口蓋に接触する者がいることも確認できた。

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A strain sensor element utilizing inverse magnetostrictive effect and magnetoimpedance effect was developed, and the strain-impedance properties of the element were investigated. The Strain-Impedance (SI) element constructed from a CoSiB/Cu/CoSiB layered film was prepared on a Corning No. 0313 glass substrate by magnetron sputtering under a magnetic field. Co₇₃Si₁₂B₁₅ negative magnetostriction films (λ= -6 × 10^-6) were selected as magnetostrictive layers, and magnetic anisotropy was induced parallel or perpendicular to the applied strain direction. In the SI element, applied strain ε was detected as a change in impedance Z, inductance L or resistance R in the range from 1 MHz to 15 MHz. By applying strain (ε =±2 × 10^-3), we dramatically changed the impedance through the change in permeability of the magnetostrictive layers. The maximum gauge factor, Gmax, which was defined as the maximum fractional change in impedance to strain, (ΔZ/Z)/ε, was 1500 - 2000 at 1 - 15 MHz. These values were much larger than those of the single-layer CoSiB element. This layered SI element will be very useful for sensing small amounts of strain.

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We found that in the three-stage rolling method, control of the intermediate annealing temperatures improves the [001] orientation and makes it possible to reduce the iron loss in silicon steels. The measured iron loss W_13/50 for an applied tensile strength of 2 kg/mm² was 0.28 W/kg, which is about 50% less than that of conventional (300-μm) grain-oriented silicon steels.

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A configuration of microstrip-line-type coils was developed for measuring electromagnetic noise. The measurement system consists of a microstrip-line-type coil array,diode switch circuits, an amplifier, and a spectrum analyzer.Some measurements of noise from a personal computer obtained by means of this system are presented.

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Magnetic micromachines are driven by magnetic fields and can be operated wirelessly. The devices themselves require no batteries and no controlling parts or machinery. Given these advantages, micromachines are expected to be applied widely in the medical field. As one example, a micromachine equipped with a heating element for hyperthermia and capable of maneuvering within the human body can be used to provide a new cancer therapy for local hyperthermia. In this study, we fabricated a magnetic micromachine capable of moving in the liver, one of the targets of local hyperthermia. The machine consisted of a cutting tip to cut the liver tissue, a cylindrical permanent magnet and a spiral structure made with a tungsten wire. The magnet was magnetized in the direction of its diameter. The machine was designed with a small diameter of only 0.9mm in order to permit the insertion of an 18G injector. When a rotational magnetic field was applied, the magnet rotated and the spiral structure produced thrust force. The micromachine was able to move a distance of 40mm in a porcine liver and 45mm in a bovine liver. These results confirm that the micromachine has excellent potential for medical applications.

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This study reports the performance of a high-frequency carrier-type thin-film magnetic field sensor that uses impedance change at high frequencies. To obtain high resolution, we reduced environmental electromagnetic noise and used high resolution instruments. A voltage change ratio (similar to the MR ratio) of 26.7% was achieved when ac carrier frequency was 400MHz. The resolution of the sensor was dc 2 × 10^-4 Oe and ac 8 × 10^-5 Oe, respectively.

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For medical equipment such as catheter or endoscope, it is required to bend its end to select the way at blanches inside of the body. We proposed a method to bend the end of the catheter using magnetic torque. By using magnetic torque we can apply the torque for bending to the magnet attached at the end of the catheter. In the experiment we used a medical guide-wire which is used to insert the endoscope. By attaching a NdFeB magnet of 0.7mm-diameter and 4.7mm-length, the guide wire bend in the curvature radius of 33mm in the field of 23.9kA/m. The bending direction and angle were controlled by 2D coils and a control system. Using this system, we could control the bending of the guide wire by stick-type controller. The obtained system is simple and wireless, obtains large enough bending, and have quick response. These properties are the most suitable point for application for medical equipment.

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We developed a near-field magnetic noise measurement system using a shielded-loop-type 432 coil array. To allow measurement of magnetic noises from 1 MHz to several hundred MHz, we took account of the voltage induced by the magnetic field in the pickup coil, impedance matching at the crossing points of lead lines, and the size of ground plane. High resolution of the measurement position can be obtained by using the XY-stage.

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We propose a new method of preparing highly oriented silicon steel sheets with a thickness of 100 μm. Our new method consists of a three-step rolling process and a two-step intermediate annealing process. The final annealing to form a (110) [001] texture takes advantage of the surface energy. The magnetic induction at 800 A/m, B₈ is about 1.9 T, and the coercive force is less than 4 A/m.

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This paper discusses the properties of a high-frequency carrier-type thin-film magnetic field sensor in a GHz band. Calculations based on bias susceptibility theory and Maxwell’s equation indicated that the properties of the sensor in the GHz band were meinly determined by ferromagnetic resonance. The high-sensitivity area shifted to the high magnetic field side when the carrier frequency was increased. The properties are greatly different from those in megahertz band. Therefore, the high-sensitivity area of the sensor can be selected by using saturation magnetization or an anisotropy field to determine the resonance frequency.

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