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Techniques for identifying defects in metals are very important in a wide variety of manufacturing areas. The present paper reports an eddy current testing method that employs a nano-granular in-gap magnetic sensor (GIGS) to detect internal defects in aluminum boards. The GIGS consists of a tunnel magnetoresistive film with nanometer sized grains and two yokes. In the presence of an external magnetic field, the nano-granular film exhibits only a small change in resistance due to the tunnel magnetoresistive effect. However, by placing it between two yokes, the magnetic flux can be greatly concentrated, thus increasing the change in resistance. The GIGS is a magnetic-field sensor that exploits this principle to achieve enhanced sensitivity. Moreover, because it has a cross-sectional yolk area of just 80 μm×0.5 μm, it achieves outstanding spatial resolution. In the present study, it is used in combination with an eddy-current method in order to detect internal defects in aluminum. In this method, an excitation coil is used to apply an AC magnetic field perpendicular to the aluminum surface. This induces eddy currents in the metal, which in turn give rise to an AC magnetic field, which is then measured by the GIGS. The presence of defects in the aluminum distorts the eddy current flow, causing a change in the magnitude and distribution of the magnetic field. Such changes can be detected using the GIGS. In the present study, the proposed method was used to successfully detect indentations with diameters of 5mm on the rear surface of an aluminum plate. [ABSTRACT FROM AUTHOR]

We propose, herein, a method by which to measure the phase of the carrier in a high-frequency carrier-type sensor (giant magneto impedance sensor). The proposed method is based on a carrier suppression technique. The phase of the carrier signal changed dramatically by approximately 180 [degrees] around the carrier suppression when a small dc field was applied. The phase sensitivity for a small dc field reached 3600 [degrees]/Oe. In addition, in the present study, we investigate the relationship between phase sensitivity and suppressed carrier level in the suppression circuit, the measured data nearly corresponded to theoretical data. Index Terms--Carrier suppression technique, giant magneto impedance (GMI), high-frequency carrier-type sensor, phase detection, thin film.

In this paper, the authors propose applying a magnetic actuator to a capsule endoscope. Capsule-shaped magnetic actuators were fabricated and in vitro tests were examined. The magnetic actuator was composed of a capsule dummy, a permanent magnet inside the capsule, and a spiral structure. The actuator was rotated and propelled wirelessly by applying an external rotational magnetic field. It was demonstrated that the actuator with 1-mm height spiral could move at 5 mm/s. In addition, the torque required to start rotation was measured. The actuator has great potential for wireless operation of the capsule endoscope. Index Terms--Actuators, biomedical equipment, magnetic fields, rotating machines.

Reports on the effect of order-disorder transition on magnetic properties of high silicon-iron single crystals. Method used to make high-silicon single crystals; Way that can change the saturation magnetization, the magnetocrystalline anisotropy constant and the saturation magnetostriction constants in such crystals; Factor to which the phenomena is attributable.

Presents a study which proposed a concept for the fabrication of magnetostrictive actuators using rare-earth terbium-samarium thin films. Methodology; Applied magnetic-field dependence of the magnetorestriction for samarium-iron thin films; Actuation behavior of the magnetostrictive bimorph cantilever.

We propose a new method to measure the permeability of striped films. The permeability can be obtained by the change in the input impedance of the film. The sensitivity of these measurements are compared with the figure-eight coil method. The sensitivity of the method is estimated over 100 times greater than a conventional figure-eight coil method. The permeability of striped CoNbZr films (100 [micro]m wide) can be measured accurately using this permeameter. Index Terms--High sensitivity, input impedance, striped film, thin film permeability.

This paper discusses miniaturization and the sensitivity of a high-frequency carrier-type thin-film magnetic field sensor. We examined a lift-off process as fabrication process instead of ion-milling process to obtain an even edge and higher sensitivity when the sensor is miniaturized. Then, we used a thin conductive interlayer to control the domain structure and demonstrated high sensitivity. The sensor dimensions were miniaturized to 3 [micro]m wide, 1 [micro]m thick and 1 mm long. In this instance, an impedance change of 3 [Omega] against external dc field was obtained. Moreover, a gain of 150 k[Omega]/T was achieved. Index Terms--Domain structure, high-frequency carrier-type thin-film magnetic field sensor, laminated sensor, lift-off.

A highly sensitive high frequency carrier-type magnetic field sensor based on the giant magnetoimpedance effect has been developed. It has been combined with a high frequency carrier suppressing circuit to reduce carrier phase noise dramatically. Highly sensitive magnetic field resolution of 8.8 x [10.sup.-7] Oe (8.8 x [10.sup.-11] T) was demonstrated. Index Terms--Carrier suppression, giant magnetoimpedance, high frequency carrier, magnetic field sensor, phase noise.

This paper reports on design criteria and characteristics of a wireless ac marker that will be used for a magnetic motion capturing system capable of sensing multiple markers. The calculation of generated magnetic fields agrees with experimental result, demonstrating usefulness for designing ac markers. These simulations indicate fields as large as 0.19 Mm can be generated at 0.1 m from the marker edge by using a ferrite of 1.5 mm diameter and a layer of 72 parallel windings of 0.11 mm diameter wire, where the copper losses is close to the core losses. Index Terms--AC marker, copper loss, core loss, motion capturing system.

We examined a laminated high-frequency carrier-type thin-film magnetic field sensor that consists of CoNbZr soft magnetic films with Nb nonmagnetic conductive interlayer. The lamination can change domain structure of the sensor and obtain high sensitivity. An impedance change of 6 [Omega] and a gain of 43 k[Omega]/T was achieved when the length of the laminated sensor was 1 mm. The gain is four times larger than that of a monolayer sensor. Index Terms--Demagnetizing field, domain structure, high-frequency carrier-type magnetic field sensor, lamination, magnetic anisotropy.

We have developed a magnetic motion capture system consisting of up to two magnetic markers (Nd--Fe--B magnet) and four three-axial sensors. The position and orientation of the magnetic makers (dipole) are detected by measuring the magnetic field of markers. Position accuracy of one marker is about 3 mm when a marker is located 150 mm from a sensor, position accuracy of two markers is about 20 nun when the markers are located 150 mm from sensors. The most common error source is cross talk between the cores of three-axial sensors. Index Terms--Inverse problem, magnetic dipole, magnetic markers, motion capture, three-axial sensor.

A remote temperature sensing system was investigated. The system can measure the temperature by applying an external magnetic flux to the sensor and by receiving a flux at the resonant frequency corresponding to the temperature at the sensor. The sensor does not need a power supply within it and is only composed of a temperature sensitive ferrite core and a wound coil. The inductance of the core varied from about 8-18 mH in the temperature region of 35-55 [degrees] C. The induced voltage, [Delta] V by the sensor was about 10 mV for a 260 mm length between the transmitter and receiver. The system was successfully operated in our investigation. Index Terms--Curie temperature, magnetic flux, remote sensing, temperature sensing system, temperature sensitive ferrite.

Vertically and horizontally aligned micro wire arrays with the magnetic hard axis perpendicular to the length of the wire are micro-fabricated from zero-magnetostrictive CoNbZr film. Annealing produced a 180-degree domain pattern, small coercive force and good permeability. Using the micro wire array with line/space = 9 [micro]m/2 [micro]m, an RF integrated inductor exhibited L = 7.5 nH(+11% of air core's), R = 7.6 [Omega] and Q = 6.3 (almost same as the air core's). Index Terms--Bi-directional micro wire array, complex permeability, domain pattern, hysteresis curve, inductance, microfabrication, quality factor, RF integrated inductor.

Improvement of magnetic thin-film inductors for RF monolithic microwave integrated circuits (MMIC's) is discussed. Surface planarization reduced the surface roughness down to [R.sub.a] = 1.2 nm, which enhanced the quality factor by 14% over a nonplanarized inductor. The orthogonal bar slit pattern was the best among the fabricated slit patterns. L = 7.55 nH (+12% of the air core), R = 6.80 [Omega] and Q = 7.09 (+9%) were obtained for the orthogonal bar slit pattern (slit width = 0.75 [micro]m) with surface planarization. Index Terms--Complex permeability, inductance, microfabrication, planarization, quality factor, RF integrated inductor.

Effect of a machine shape on swimming properties of the spiral-type magnetic micro-machine was examined by using a finite volume method. The optimum design of the blade shape was obtained by using the results of the simulation. According to the optimum design, the micro-machine was fabricated by a stereolithography. The swimming properties of the machine were agreed well with the analyzed results. Index Terms--micro-machine, spiral blade, finite volume method, stereolithography.

A bridge-connected high-frequency carrier-type thin-film magnetic field sensor is fabricated on a SmCo magnetic thin-film which provides an in-plane dc bias magnetic field to the sensor. The dc bias field of 320 A/m was achieved by using a 3 [micro]m thick SmCo underlayer. The sensitivity obtained was 8.4 mV/Oe which was 12 times as large as the sensitivity without the SmCo thin-film magnet. Index Terms--SmCo thin-film magnet, high-frequency carrier-type thin-film magnetic field sensor, non-uniform bridge-connected sensor, GMI sensor

Amorphous CoZrNb thin films were deposited on amorphous SmCo thin films. The amorphous SmCo layer generated magnetic bias field for the soft film, and this bias field was increased as the length of easy direction was reduced. The bias field of 60Oe was measured for the sample with the dimension 3mm x 0.5mm. The magnetization process of the biased soft film was different from that of a single layer film. Index Terms-SmCo, CoZrNb, Bias field, domain

An optical scanning electromagnetic field probe system consisting of an optic crystal substrate and a galvano scanner has been developed for high speed, low-invasive measurement of electromagnetic near field distribution. We measured magnetic field distributions above a microstrip line using several magnetic garnet crystal substrates and the probe system. We observed that the frequency response in the gigahertz range improved when we applied a magnetic bias to the crystal. In addition, a magnetic field component in a particular direction could be detected by controlling the direction of the magnetic bias. [ABSTRACT FROM AUTHOR]

Integration of the exciting coil and the pick-up coil array for the wireless magnetic motion sensing system has been investigated to clear the limitation of the system arrangement. From the comparison of the integrated-type and the sandwich-type, which was proposed by our previous study, regardless of the lower signal-to-noise ratio of the integrated-type than that of the sandwich-type a repeatable detection accuracy of around 1 mm is obtained at the distance of 120 mm from the pick-up coil array (sandwich-type: up to 140 mm). A different tendency of the detection errors in detection was also observed. In spite of different tendency, the cause of the errors has been clarified. The impedance change of the exciting coil due to a resonance of the LC marker perturbs strength of the magnetic field which is used for marker excitation. However, the errors are able to compensate to the actual positions and orientations of the marker by using compensatory method which was already established. [ABSTRACT FROM AUTHOR]

We have proposed a magnetic motion capture system using an LC resonant magnetic marker. The proposed system is composed of an exciting coil, an LC marker, and a 5×5-matrix search coil array (25 search coils). The LC marker is small and has a minimal circuit with no battery and can be driven wirelessly by the action of electromagnetic induction. It consists of a Ni–Zn ferrite core (3 mm[lowercase_phi_synonym]×10 mm) with a wound coil and a chip capacitor, forming an LC series circuit with a resonant frequency of 186 kHz. The relative position accuracy of the system is less than 1 mm within the area of 100 mm3 up to 150 mm from the search coil array. Compared with dc magnetic systems, the proposed system is applicable for precision motion capture in optically isolated spaces without magnetic shielding because the system is not greatly influenced by earth field noise. [ABSTRACT FROM AUTHOR]

By the sterolithography technique and the ferrite plating, we fabricated three types of magnetic micromachines which coated Fe[SUB3]O[SUB4], Co[SUB0.39]Fe[SUB2.61]O[SUB4], and Co[SUB0.45]Fe[SUB2.55]O[SUB4], respectively. The stereolithography technique enables one to form the spiral-shape resinous templates and the ferrite plating enables one to coat the ferrites uniformly onto these templates from an aqueous solution. The total machine weight is light because a resin of the template body is almost the same density as water. We verified that the machines swim freely and wirelessly in water by applying a rotational magnetic field. As these machines coated with ferrites have the biocompatibility, there is the possibility of medical microrobots which swim in the human body for medical operations. [ABSTRACT FROM AUTHOR]

We developed the fully automatic permeameter which is made of driving plates and shielded loop coil available in 1 MHz–3GHz. We clarified the sensitivity of the permeameter and the sensitivity can be explained by an uncertainty of network analyzer. We evaluate the permeability of striped CoNbZr films (50, 20, 10 μm wide). A reasonable relation between permeability spectrum and domain observations can be demonstrated. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Examines the dynamic magnetic domain and eddy current loss of silicon-iron tape-wound cores. Methods for observing dynamic magnetic domain patterns; Photographs and computer simulations of the dynamic domain pattern; Dependence of the velocity of each domain wall on the drive frequency.

Investigates the effect of impurities on the tertiary recrystallization and magnetic properties of the thin silicon steels. Dependence of magnetic induction and coercive force on annealing time; Relationship between annealing temperature and the Β[sub8] of the sample; Dependence of the completion of tertiary recrystallization on pre-annealing time.