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Complex relative permeability and permittivity were evaluated simultaneously in the band of 100 MHz–67 GHz using a flexible microstrip line-type probe. In principle, the probe can evaluate the permeability and permittivity of electromagnetic materials regardless of size. The measured permeability and permittivity were obtained from the transmission coefficient (S21). Since S21 under the infinite magnetic field can be estimated by changing the DC magnetic field stepwise, the magnetic and dielectric signals were separated accurately. The complex permeability and permittivity of an NiZn ferrite sheet (10 mm × 10 mm, 0.1 mm thick) and polytetrafluoroethylene (PTFE) (25 mm × 25 mm, 0.79 mm thick) were evaluated accurately.

Magnetic hyperthermia is a promising cancer therapy gaining great interest in recent years. In this therapy, in addition to magnetic particles, important elements include techniques for detecting the position and temperature of magnetic particles in a tumor region in determining the effectiveness of therapeutic heating. In previous studies, we developed a low invasive heating and wireless temperature measurement system for magnetic hyperthermia using a ferromagnetic implant with low Curie temperature (FILCT). To make this approach feasible in clinical settings, a challenge remains when the FILCT injected into the tumor region deviates from the central axis of drive coil. As a result, the heating efficiency of FILCT and the temperature measurement accuracy of FILCT decrease. In this study, we develop an automatic localization system for magnetic particles. Using the constructed system, it was possible to automatically locate the position of magnetic particles with an accuracy below 1 mm in vitro by operating magnetic field supply and detection (MFSD) unit in two modes of coarse scanning (rotary scanning) and fine-tuned scanning (linear scanning) based on three pickup voltages induced in three pickup coils symmetrically installed inside drive coil.

A highly sensitive microstrip-line-type probe using a flexible substrate was developed to measure thin-film permeability continuously up to the millimeter-wave frequency range (over 30 GHz). The probe enables broad bandwidth and highly sensitive permeability measurements without sample size limitations. The complex permeability of the CoFeB film (45 mm $\times25$ mm and $0.5~\mu \text{m}$ in thickness), CoNbZr film (25 mm $\times25$ mm and 3 nm in thickness), and nickel ferrite film (8 mm $\times5$ mm, and $1.2~\mu \text{m}$ in thickness) were optimized. The measured permeability spectrum and ferromagnetic resonance frequency showed good agreement with the theoretical values based on the Landau–Lifshitz–Gilbert equation and eddy current generation up to 67 GHz.

Magnetic hyperthermia with magnetic nanoparticles (MNPs) has been introduced to selective treatment of tumor and the MNPs also has demonstrated diagnosis. For non-invasive treatment, a therapeutic platform with temperature monitoring that can avoid overheating in normal tissues is of vital importance. In this study, we have developed a wireless temperature monitoring system by utilizing the combination of magnetic harmonic signals of the MNPs for magnetic hyperthermia treatment in laboratory experiments. We achieved an accurate measurement with an error of 0.18 °C. For practical use on breast/oral cancer, a detectable distance of at least 10 mm is required. To demonstrate the feasibility toward future biomedical applications, we investigated the dependency on the amount of Resovist® and the error is less than 0.5 °C in a 10 mm distance. Our system can measure the correct temperature regardless of Resovist amount. The results indicate that our system can apply for monitoring temperature on magnetic hyperthermia treatment.

In this study, we aim to develop gold-coated Fe3O4 nanoparticles (Fe3O4@Au NPs) as theranostic agents for magnetic hyperthermia and CT imaging applications. The Fe3O4 NPs were synthesized via thermal decomposition method, and the gold was then deposited onto the surface of Fe3O4 NPs by reducing gold acetate at 190 °C. The average sizes of Fe3O4 and Fe3O4@Au NPs were 5.2 nm and 6.1 nm, respectively, which are effectively removed by the kidneys. The magnetization of Fe3O4@Au NPs (9.7 emu/g-Fe3O4) at 300 K was much smaller than that of Fe3O4 NPs (52.4 emu/g-Fe3O4). The heating efficiency of Fe3O4@Au NPs in water was sufficient to treat the tumor at 43–45 °C, and their high CT value of 851 HU was obtained. The synthesized ultrasmall Fe3O4@Au NPs showed great promise as a potential theranostic agent for magnetic hyperthermia and CT imaging applications.

A novel method for measuring the complex magnetic susceptibility of magnetic nanoparticles (MNPs) has been developed by a broadband microstrip line-type probe with a frequency range of up to 50 GHz. Two external orthogonal DC fields, Hhard and Heasy, were applied to change the susceptibility of MNPs (Streptavidin coated, 200 nmϕ, number of MNPs about 1010) based on magnetization switching theory. The susceptibility of MNPs in the liquid, solid state, and after biotin-avidin reaction with polymer beads (2 μmϕ, number of polymer beads about 108) was evaluated. A clear FMR frequency of MNPs and the same FMR frequency shift trend as Hhard changed was observed around 2–10 GHz in both liquid and solid states. The susceptibility of MNPs reached maximum when Hhard was 0.1 T which is approximately equal to Heasy (0.135 T). The maximum values of real and imaginary parts increased by a factor of 3.39 and 1.66 compared to when Hhard was 0. The obtained results indicate that the magnetic anisotropy was successfully controlled in the liquid and solid states of MNPs aggregate. Furthermore, after the biotin-avidin reaction of MNPs with polymer beads, the imaginary part of susceptibility showed a decreasing trend regardless of the increase in Hhard, and its half-width expanded by 35.1% at maximum when Hhard was 0.15 T.

In this study, we prepared ultrasmall FeCo nanoparticles (NPs) with a high magnetic moment and examined their antigen-antibody reaction for biodetection applications. The FeCo NPs were collected from the FeCo-BaF2 nanogranular film with Fe:Co:Ba:F = 14:11:21:54 at.%, by dissolving the film in water since the BaF2 matrix was deliquescent. The size of FeCo NPs was ∼5 nm and the saturation magnetization was estimated to be ∼15.30 kG (149.0 emu/g). The Candida albicans antibodies (abcam ab53891)-conjugated FeCo NPs were collected by using an ultracentrifugal separation (110 000 rpm, 90 min), they were then reacted with Candida albicans. The obtained result indicates that Candida albicans were absorbed successfully onto FeCo NPs, and the number of Candida albicans bound to FeCo NPs counted from the micrographs of the aggregates of FeCo NPs and Candida albicans increased significantly by adding sonication treatment of the film in water before binding them to the antibodies. The success of antigen-antibody reaction of ultrasmall NPs with high magnetic moment improves detection sensitivity as well as offers potential detection for smaller biomolecules.

We have proposed coplanar line type thin-film magnetic field sensor with narrow slits. The slit is employed to flow more carrier current on the signal line by improving the impedance matching. Several sensors having 6, 10, 26, 36, and 50 μm slit widths were fabricated and evaluated from the phase and the amplitude of the transmission coefficient ( S21) and reflection coefficient ( S11) measured by the network analyzer. The amplitude of S21 with slit was improved about five times larger than the sensor without one at around 2 GHz. The appropriate slit width was evaluated as around 10 μm for the coplanar line type thin film magnetic field sensor and the sensitivity will enhance more than 10 times higher than the sensor without slits.

Alternating magnetic fields can deliver magnetic energy deeper inside the body for magnetic hyperthermia cancer therapy by using magnetic nanoparticles (MNPs). In this study, we proposed a highly effective heat generation method for the MNPs by the application of an ultra-short pulse wave. We numerically evaluated the heating power with a variety of parameters, such as pulse width, field amplitude, and frequency. The hysteresis curve and magnetization dynamics clearly indicate larger energy dissipation. Hysteresis loss and the input energy increase with increasing field strength and duty ratio and there is a large efficiency power condition. To evaluate the effective heat generation and practical temperature increment, a larger imaginary part of magnetic susceptibility (χ″ > 30) and specific loss power (SLP > 105 W/kg) are required. In addition, larger intrinsic loss power (100 nHm2/kg) is achieved. The results indicate that the contribution of magnetic harmonics signals on the ultra-short pulse wave significantly enhances the heat generation of MNPs for cancer therapy.

Virus detection methods based on nonlinear magnetic response of magnetic nanoparticles have been investigated, and magnetic detection methods using the third harmonic are widely applied, owing to their high sensitivity and short measurement time. This paper proposes a virus detection method based on the second harmonic because of its larger signal component. We found that the second harmonic signal is superior to the third harmonic signal for small nanobeads and a large change of the second harmonic signal in the signal-to-noise ratio (SNR) with nanobeads concentration. In addition, a virus detection limit of 100 pg/ml is achieved. Therefore, the proposed method can potentially be utilized for rapid screening of viruses.

We propose a novel method based on the inverse problem approach to optimize the shape of a magnet generates high uniformity of magnetic fields in a magnetometer with diamond nitrogen-vacancy (NV) centers. Our original method can determine the combination of magnetic moments required to design a unique magnet shape. We obtained a unique shape of the small magnet (optimized model, 15 × 15 × 25 mm3 and 25 × 25 × 15 mm3) for integrated magnetometry system and improved the magnetic uniformity from 83.6% to 99.0% in the diamond NV centers area ( X = −1–1 mm, Y = −1–1 mm, Z = 5–6 mm). The results indicate a highly sensitive magnetometer with a diamond NV center for future biomedical applications.

We investigate the frequency dispersion of complex permeability in the GHz range in superparamagnetic nickel–zinc ferrite thin films with different Ni/Zn ratios using a microstrip probe. The films, comprising crystallites as small as 3 nm and deposited by a microwave-irradiation-assisted solvothermal method, exhibit the coexistence of two resonance characteristics—a ferromagnetic resonance peak ([Formula: see text]) at ∼2 GHz and a superparamagnetic resonance peak ([Formula: see text]) above 20 GHz, breaching Snoek's limit. The high value of [Formula: see text] is attributed to the high surface anisotropy and far-from-equilibrium distribution of cations in the lattice, while [Formula: see text] is attributed to the thermally driven superparamagnetic relaxation of ferrite nanocrystallites in the thin films. This work demonstrates the feasibility of employing superparamagnetic ferrite thin films so deposited as excellent CMOS-integrable magnetic components for high-speed and high-frequency electromagnetic device applications.

We have fabricated a high quality magnetic Ni0.5Zn0.5Fe2O4 ferrite powder/polymer composite sheet consisting of common and environmentally friendly elements only. The sheet was then tested for its dynamic permeability by irradiating with electromagnetic waves with frequencies up to 50 GHz. Two different originally developed methods were used for the high-frequency permeability measurements, a short-circuited microstrip line method and a microstrip line-probe method. It is challenging to measure the dynamic permeability of magnetic thin films/sheets beyond 10 GHz because of the low response signal from these materials. However, the two methods produced essentially equivalent results. In the frequency dependent permeability profile, the maximum position of the profile, $$\mu ^{\prime \prime }_{max}$$ μ max ″ , shifted towards higher frequencies upon increasing an applied (strong) static external magnetic field, $$H_{dc}$$ H dc . A linear relationship between $$\mu^ {\prime \prime }_{max}$$ μ max ″ and $$H_{dc}$$ H dc for the entire range of $$H_{dc}$$ H dc was observed even at small $$H_{dc}$$ H dc . In general, the spinel-structured Ni-based ferrites exhibit low magnetic anisotropy, but the present sample showed a uniaxial-anisotropic behavior in the parallel direction of the sheet. Our Ni0.5Zn0.5Fe2O4 powder/polymer composite sheet thus exhibits high performance at GHz frequencies, and should be applicable e.g. as an anisotropic electromagnetic wave-interference material.

Hyperthermia utilizing magnetic particles has been widely studied as a possible method for cancer treatment in recent years. This method induces apoptosis (cell death) using heat generation from magnetic particles which are injected into a tumor region and subjected to an external high-frequency magnetic field. In previous studies, we succeeded in developing microsize thermosensitive ferromagnetic particles with a low Curie temperature of around 40–45 °C as a self-controlled heating element that possibly prevents the local overheating surrounding healthy tissues. Further, by utilizing the change of its permeability around its Curie temperature resulting in the change in the magnetic flux density around tumor region, we also developed a wireless temperature measurement. In addition, to localize magnetic particles which cannot be seen from the body surface, we also developed an automatic localization system by using a robot arm equipped with three detection coils symmetrically installed in heating coil. To make our proposed elemental technologies feasible in clinical settings, we have also been developing a magnetic hyperthermia system that can treat deep-seated tumors up to 5 cm. In this paper, we report our elemental technologies which have been developed so far such as heating elements, temperature and position monitoring technologies.

Co/Ti-substituted Sr-based M-type hexagonal ferrite containing composite sheets are used for the demonstration of electromagnetic noise suppression at and above 6 GHz. Three different compositions (SrCoxTixFe12 − 2xO19 with x = 1.0, 1.2, and 1.4) and two different size groups with the average diameter of ∼10 µm and ∼1 µm have been studied to understand the effect of Co-Ti substitution level and size on the high frequency magnetic characteristics of SrM hexaferrites. A drop in coercivity from 285 Oe to 40 Oe and 710 Oe to 90 Oe was observed as the Co/Ti substitution level, x, increases from 1.0 to 1.4 in the case of 10-µm and 1-µm particles respectively. Complex permeability was measured by two methods – by microstrip probe, and by all-shielded and shorted microstrip line. Ferromagnetic resonance frequency drops from ∼20 GHz to ∼3 GHz as x increases from 1.0 to 1.4, while it decreases a little as the particle size decreases. Electromagnetic noise suppression was demonstrated by measuring the ratio of power loss in the magnetic element to the input power by placing it on top of a microstrip line. With a 500-µm thick composite sheet, electromagnetic noise suppression up to 20% was achieved.

For tracking position or motion of objects in small or shielded spaces, our wireless position-detection system using an LC resonant marker is considered to be effective. Generally, detection of the accurate position of the marker is difficult when reduction of the $S/N$ ratio occurs due to the marker posture. To solve this problem, we propose a system with four excitation coils to generate four-directional magnetic fields whose components are different from each other. To evaluate this system, simulations and experiments were conducted for a single excitation coil and for four excitation coils. In the single excitation coil system, position detection was difficult for some postures of the LC marker due to the greatly reduced excitation efficiency of the marker. In contrast, in the four excitation coil system, the excitation strength of the marker was kept for every marker posture, and position detection was performed with high accuracy even when the marker was placed where the excitation was weakest. Therefore, it is possible to detect the position of the marker accurately regardless of its posture by using four excitation coils. By this improvement, our position-detection system is considered to be useful for tracking finger motion in some applications.

The spin dynamics in magnetic thin films have attracted much attention from both fundamental and application viewpoints. The dynamics are described using the phenomenological Landau-Lifshitz-Gilbert (LLG) equation consisting of both the precession torque of the magnetization and the damping torque. Especially, a Gilbert damping constant (α), which describes the strength of damping torque, is one of the dominant parameter to predict the dynamics. Until now, we reported the correlation between α and the saturation magnetostriction $( \lambda _{\mathrm {s}})$ for Ni-Fe and Ni-Fe-M films[1]–[3] and found different behaviors of α depending on positive or negative values of $\lambda _{\mathrm {s}}$. To investigate this correlation in more detail, these parameters must be estimated simultaneously for each film using a same measurement instrument. Herein, we proposed a new measurement technique, which employs a microstripe line probe to detect ferromagnetic resonance (FMR) spectra for a magnetic thin film either with tensile stress or stress free, which enables simultaneous evaluation of α and $\lambda _{\mathrm {s}}$

Thin-film type magneto-impedance (MI) elements having widths and thicknesses of several micrometers and lengths less than 100 μm in a rectangular shape were fabricated to reduce the demagnetizing effect. Triangular-type MI elements with sensing parts less than 100 μm in length were also fabricated to facilitate near-field detection with a higher spatial resolution. Rectangular-type elements with widths and lengths of 2 μm and 30 μm, respectively, demonstrate a typical MI profile, whereas an element with a 1 μm width shows a discontinuous impedance change and hysteresis due to incomplete anisotropy control. For the triangular elements, we can suppress the distribution of the demagnetizing factor in the sensing part of the elements and obtain typical MI profiles for 30-100 μm lengths.

Highlights • Magnetoelectric effect in the nanogranular FeCo-MgF films has been investigated. • Magnetoelectric effect and dielectric relaxation are confirmed at frequencies over 10 MHz. • The inter-spacing of granules and the relaxation time decrease with increasing magnetic metal concentration. • The magnetoelectric effect reaches a maximum at a relaxation frequency., The magnetoelectric effect is a key issue for material science and is particularly significant in the high frequency band, where it is indispensable in industrial applications. Here, we present for the first time, a study of the high frequency tunneling magneto-dielectric (TMD) effect in nanogranular FeCo-MgF films, consisting of nanometer-sized magnetic FeCo granules dispersed in an MgF insulator matrix. Dielectric relaxation and the TMD effect are confirmed at frequencies over 10 MHz. The frequency dependence of dielectric relaxation is described by the Debye-Fröhlich model, taking relaxation time dispersion into account, which reflects variations in the nature of the microstructure, such as granule size, and the inter-spacing between the granules that affect the dielectric response. The TMD effect reaches a maximum at a frequency that is equivalent to the inverse of the relaxation time. The frequency where the peak TMD effect is observed varies between 12 MHz and 220 MHz, depending on the concentration of magnetic metal in the nanogranular films. The inter-spacing of the films decreases with increasing magnetic metal concentration, in accordance with the relaxation time. These results indicate that dielectric relaxation is controlled by changing the nanostructure, using the deposition conditions. A prospective application of these nanogranular films is in tunable impedance devices for next-generation mobile communication systems, at frequencies over 1 GHz, where capacitance is controlled using the applied magnetic field.

This study describes a user-friendly and rapid detection system of oral bacteria in the liquid phase for point of care testing based on magnetic immunoassay. We focused on the dependence of the strength of external magnetic field required to switch the magnetic moments of nanoparticles bound to bacteria on the bacteria concentration. The results obtained indicate that the required field strength increases linearly as a function of log concentration of Porphyromonas gingivalis cultured in the range of 103–109 CFU/mL. Similarly, the required field strengths for Streptococcus mutans and Pseudomonas aeruginosa increase monotonically when their concentrations increase, whereas the required field strength for Escherichia coli decreases monotonically when its concentration increases. We then measured the concentration of Porphyromonas gingivalis in the saliva collected from elderly people in a geriatric health services facility and the results using the developed system had a correlation with those using a commercial bacteria counter.

A very sensitive thin-film sensor was developed using a meandering coplanar line fabricated from Sr33Ti16O51 film (3 $\mu \text{m}$ thick), amorphous Co85Nb12Zr3 film ( $1~{\mathrm{ mm}} \times 2.45$ mm, 0.3–2 $\mu \text{m}$ thick), and Cu/Cr film (2/0.1 $\mu \text{m}$ ). The deposited SrTiO film enhanced the sensitivity of a magnetic field sensor, a phase change of more than 30°/Oe and a gain of over −40 dB being achieved simultaneously. The maximum phase change (sensitivity) was observed for a CoNbZr film thickness of $\sim 0.5$ –1 $\mu \text{m}$ . The sensitive bias field and carrier frequency increased as the CoNbZr film thickness increased. The optimum CoNbZr film thickness was realized by the tradeoff between the sensitive bias field and the volume of the CoNbZr film.

A new tracking system utilizing a nasogastric tube with a wireless resonated marker was developed. A narrow marker (2 mm wide and 37 mm long) was fabricated and inserted into a commercial nasogastric tube. A good quality factor of about 136 was obtained. Positional accuracy within about 10 mm was obtained when the marker was scanned for about 100 mm. The nasogastric tube was roughly tracked inside a rabbit. A reasonable and reproducible profile of the tube was measured when the tube was inserted through the mouth into the esophagus of the rabbit.

sensor5) can be operated at room temperature; however, they are comparatively large in scale, making it difficult to integrate them in a sensor array. Highly sensitive magnetic field thin film sensors operating at room temperature are useful for biomedical applications or nondestructive evaluation. Thus, development of a thin film sensor to measure biomagnetic signals at room temperature was the aim of this study. As previously reported, a coplanar line-type thin film sensor with a ceramic substrate (r = 115) to enhance sensitivity of phase change was developed 6) and successfully used to obtain magnetocardiograms (MCGs) at multiple points7). The ceramic substrate with high permittivity decreases the wave length of the carrier, the phase dramatically changing when a small field is applied. However the sensor is bulky and cannot be integrated. In the present study, we developed a thin film integrated sensor including magnetic thin film, dielectric film and conductive film. These structure can be easily developed for array sensors with the same characteristics. The goal of this study was to obtain a sensor with good characteristics (phase change > 100 degree/Oe, gain > -40 dB) for obtaining magnetocardiograms 7) .

With the aim of improving the detection accuracy of a wireless magnetic position-sensing system using an LC resonant magnetic marker, a pickup coil with an optimal size (10 mm in diameter × mm thick), as calculated by a previous simulation study, was used and tested in this paper. Our study confirmed that positional errors were reduced to a submillimeter order in the area within y=120 mm from the pickup coil array. On the contrary, in the area outside y=130 mm from the pickup coil array, the errors increased by about 0.5-2 mm compared to the results for the previous pickup coil size (25 mm in diameter × 2 mm thick). Regardless of the size of the pickup coil, however, compensation can be made for these positional deviations, including the influence of the mutual inductance between the LC marker and the exciting coil. After application of the compensation process, the detection results were corrected approximately to the actual positions of the LC marker.

Septum systems are the most important devices for beam injection and extraction in circular particle accelerators. Because of the high-field requirements with a thin septum structure, septa have major problems with heating and cooling of coils and there is a possibility that a mechanical breakdown of coils occurs due to magnetic forces in a pulsed operation. These problems are exacerbated by the long pulse excitation of large inductance magnets because of their multi-turn coils for high-field production, keeping a flat top accuracy of less than 0.1%. Recently the pulsed field techniques of fast rise and field higher than 0.5 T have been realized in the study field of kicker magnet systems, which can be used to solve the above-mentioned problems. This paper focuses on fast beam injection/ejection methods by using a short-pulsed septum magnet.

A fast-rise trial has been performed using auxiliary magnets, which are excited by damped oscillation. There is a possibility to achieve faster rise-time using a simple structure than a delayed line type magnet. A favorable result was obtained by the method. The outline of this scheme and the representative experimental results are described in this paper.

A highly sensitive and broadband method of obtaining the permeability of magnetic film without limitations in sample size was developed based on the high frequency impedance of microstrip meander probe and magnetic film. The probe (5.6 mm × 5 mm, 2 turns) was scanned in the vicinity of a CoNbZr thin film (50 × 50 mm, 0.1 μm thick), and the permeability was optimized by Newton-Raphson method in a frequency range of 10 MHz - 8 GHz. The measured values roughly corresponded to theoretical values based on the Landau-Lifshitz-Gilbert equation and eddy current generation. The proposed method shows promise for measuring the permeability of wafer-sized samples in-line because it is not restricted by size limitations.

We have developed a very sensitive transmission line-type thin film sensor. The sensor, consisting of a coplanar line, SiO2 film, and amorphous CoFeSiB film, was fabricated by sputtering, lift-off, and lithography processes. A phase change of 45 degrees/Oe was obtained at 1 GHz. We arranged two-dimensional stepping motors and developed a scanning system for the sensor. Aluminum samples with through holes were examined by using the eddy current method. Aluminum wires with small Fe balls as impurities were tested by measuring the DC field.

A position-detecting system made up of a nasogastric tube using a wireless LC resonated magnetic marker has been developed. The marker, consisting of an inductor and a capacitor without battery or electric wires, was installed inside a commercial nasogastric tube. A positioning accuracy within 7.1mm was obtained when the marker inside the tube was parallel translation to 100mm. The marker inside the tube was roughly tracked in the esophagus and trachea of a human model.

The effect of an electric field has been treated as smaller than that of a magnetic field in the control of a high-energy beam orbit, and it has been ignored in the magnets of almost all high-energy particle accelerators. There is currently a strong demand for high-energy accuracy field performance of the order of 1% in pulsed magnets to suppress beam loss at injection/ejection in high-intensity particle accelerators. The effect of the electric field increases as particle energy decreases. The electric field induced in a gap of pulsed magnets is complex as its characteristics vary with time and space. Here, electric field contributions to various kicker magnet systems are summarized.

This paper describes our proposed measurement technique for the magnetization dynamics in thin films, which employs a microstripe line probe to detect ferromagnetic resonance (FMR) spectra for a film sample either with or without tensile stress. By measurement of FMR frequency shifts using Lorentzian fits to the FMR spectra for a film with and without tensile stress, saturation magnetostriction (λs) can be determined. The measured values were compared with those estimated by the optical cantilever method using the same samples in good agreement. At the same time, a Gilbert damping constant (α) was determined using both the FMR frequency and the FMR linewidth for the tensile stress free film. The results of the experiment demonstrate that our proposed measurement technique allows for more precise evaluation of magnetization dynamics by providing information on both α and λs simultaneously for an individual sample.

We have developed a jaw tracking system with wireless resonated markers. The system consists of two resonated markers, driving coil, 40 pickup coils, DA converter, and AD converters. The two resonated markers were composed of a coil with NiZn ferrite and tip condenser. We attached to one marker on the incisor and the other on the forehead. Position accuracy of within 1 mm was achieved when the fabricated jaw model was moved about 40 mm. This system is available for tracking of reasonable jaw movement of normal subjects without disturbing the physiology.

A detection technique having an accuracy of better than 1 mm is required for body motion analysis in the field of medical treatment. A wireless magnetic motion capture system is one such effective detection technique. We propose a candidate system using an LC resonant magnetic marker (LC marker). Previous studies have showed that the system is capable of repeatable position detection accuracy of better than 1 mm if the system has an adequate signal-to-noise (S/N ratio). However, there are some cases in which the detection results include unignorable errors because some approximations, e.g. a magnetic dipole assumption of the LC marker, are applied to solve the inverse problem to determine the position and orientation of the LC marker. Therefore, a numerical analysis is employed to realize a motion capture system having a high detection accuracy. To elucidate the problem of detection error, the influence of variations in the sizes of the LC marker and the pick-up coil are considered in the numerical simulation. After studying the analysis, the main cause of detection error is determined to be the size of the pick-up coil rather than the size of the LC marker. It was also is found that a pick-up coil measuring 10 mm in diameter with a wound coil width of 1 mm achieves a detection accuracy of better than 0.1 mm.