We have produced non-controlled magnetically levitated motors using HOPG, a room-temperature diamagnetic material. These non-controlled magnetically levitated motors are vertical type, and a permanent magnet arrangement is used to levitate the rotor. Magnetic bearings were required at the top and bottom of the non-controlled magnetically levitated motor for radial stabilization. To obtain sufficient stability, permanent magnets attached above and below the rotor shaft are used to generate eddy currents in a fixed copper block to stabilize the rotor when it becomes unstable in the radial direction. For this reason, non-controlled magnetically levitated motors up to now have a relatively large number of parts and a complex structure. Here, we propose non-controlled magnetically levitated motor that reduces the number of parts as much as possible, has a simpler structure than conventional non-controlled magnetically levitated motors, and can rotate at even higher speeds.

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This paper proposes a method to reduce cogging torque by designing the permanent magnet shape of a single axial gap motor. This motor has a structure in which the rotor rotates opposite the stator and is capable of achieving both a flat structure and high torque density, but it has the problem of generating cogging torque, which causes noise and vibration. Previously, the authors proposed a multiplication wave type permanent magnet and confirmed that it is useful for reducing cogging torque. Based on this, in this study, we aimed to cancel out each harmonic component of the cogging torque by arranging the multiplication wave type permanent magnet symmetrically at the periodic boundary. Analysis using 3DFEM confirmed that the cogging torque was significantly reduced while maintaining the torque.

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An axial gap type maglev motor with 3-pole magnetic bearings has been developed. The maglev motor is for use in an implantable pediatric ventricular assist device. There are two impeller suspension control methods for the 3-pole magnetic bearing: centralized control and distributed control. This paper investigated the stability and power consumption of the maglev motor driven with the above two control methods for impeller suspension during pump operation in a closed loop circulation circuit. The developed maglev blood pump indicated a flow rate of 0-3.0 L/min against a head pressure of 60-100 mmHg at a rotating speed of 3000-5000 rpm. Maximum oscillation amplitudes of the impeller axial position and inclination are 0.02 mm and 0.80 deg with power consumption of 0.4-1.3- W in decentralized control, 0.04 mm and 0.65 deg with power consumption of 0.3-1.2 W in decentralized control. The maglev motor with the centralized control indicated advantages of enhancing the inclination sup-pression performance and reduction power consumption.

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Transcutaneous energy transmission system is a method of supplying power wirelessly to the ventricular assist device(VAD). However, there is a problem of high-frequency patient leakage current caused in the body during actual use. To suppress this leakage current, this study investigated the effect on the leakage current of a three-layer transmitting coil by changing the layer order of coil as well as by balancing the compensation circuit. As a result, when converted to 15 W transmission to VAD at 400 kHz, the minimum leakage current was 2.5 mA for the type in which the primary and secondary compensation circuit were balanced and the second layer of the transmission coil was in touch with the skin. This value was less than the regulation value of 10 mA. Furthermore, the leakage current was suppressed by 98.8% at maximum compared to the condition in which no balancing was performed.

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We have developed a hybrid magnetorheological transmission in total artificial hearts with maglev motors. The developed transmission has small size and the sufficient transmission performance, but it generated radial magnetic force that may cause touchdown in the total artificial heart. In this paper, we proposed a novel hybrid magnetorheological transmission utilizing axial and radial magnetic flux to reduce radial magnetic force. First, we showed the relationship between output rotational speed and magnetic flux density distribution in each direction. Second, we designed the hybrid magnetorheological transmission that permanent magnets were incorporated in both output shaft and yoke. Analyzed results showed that axial and radial magnetic flux density were 0.038 and 0.091 T at 0 A, respectively. From experimental results, the difference between input and output rotational speed changed from 9 rpm to 228 rpm when we applied current at 1 A. And the measured radial magnetic force of the proposed transmission was 82.1% smaller than that of the previous transmission using only radial magnetic flux.

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In this paper, we report a prototype of a total artificial heart with a homopolar type of magnetic levitation motor. This motor's outer diameter and height are 50 mm. A rotor with an outer diameter of 14 mm is placed inside a stator with an inner diameter of 18 mm, and the radial position and radial tilt are actively controlled through a clearance of 2 mm. The axial position is passively supported by the magnetic system’s stability. We introduce a mechanism that adjusts left-right blood flow balance by MR fluid transmission, utilizing axial displacement due to the left-right atrial pressure difference. By preload response test, a displacement performance is 0.07 mm with a 5-mmHg pressure difference. To reach a target axial displacement of 0.5 mm, we conducted 3D magnetic field analysis and propose a method for reducing the magnetic system's restoring force when the impeller is axially displaced.

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Electromagnetic waves are used in various applications, and thus, their biological effects are being investigated. The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has established guidelines for exposure limits to non-ionizing radiation. However, studies on frequencies in the 300 kHz to 10 MHz range are particularly lacking, necessitating further research. In previous studies, exposure of mice to a 400 kHz magnetic field suggested that it affected motor activity and brain substances. In this study, four behavioral tests were conducted to evaluate anxiety-like behavior, depression-like behavior, and spatial working memory. Although no significant differences were observed in anxiety-like behavior, depression-like behavior, or spatial working memory, it is worth reporting that the magnetic field might increase anxiety-like behavior.

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Wheat is a crop with high self-sufficiency and consumption rates worldwide. So, an increase in production and food self-sufficiency due to enhanced seed germination is expected. The seed surface is covered with a hydrophobic lipid layer, and normal germination requires a certain amount of time for water absorption. In this study, we focused on Atmospheric Low-Temperature Plasma (ALTP), which is effective for surface activation/modification and the generation of active species. ALTP irradiation promoted germination and induced hydrophilic functional groups on the seed surface. Therefore, it is considered that ALTP irradiation improved the hydrophilicity of the seed surface and facilitated germination. In this paper, the water contact angle of the seed surface was measured, the seed surface was observed using scanning electron microscopy (SEM), functional groups were analyzed by Fourier transform infrared spectroscopy (FTIR), and the germination enhancement effect and germination rate were evaluated.

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In this paper, the authors examined the possibility of detecting the magnetic field emitted by a magnetized CE (Capsule Endoscope) when a magnetic guiding magnet is used to guide the CE. As a result, it was found that it is possible to detect the position of the CE at a distance of 40 mm in a geomagnetic environment and 50 mm without considering the influence of geomagnetism.

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Smart glasses (SG) are glasses-type devices that use augmented reality technology to simultaneously display both the real world and digital information in the wearer’s field of view. By combining SG with bone conduction headphones and implementing voice recognition applications, hands-free operation can be achieved. In this study, we developed educational content for Extracorporeal membrane oxygenation (ECMO) priming using SG and evaluated its educational effectiveness. Thirty students were divided into two groups, and learning was conducted using either a paper manual or SG. The practical skills before and after the learning sessions were assessed using checklists, questionnaires, and eyetracking analysis. Additionally, clinical engineers with more than five years of hospital experience performed the procedure, and their eye movements during the procedure were analyzed for comparison.

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We investigate the squeeze effect by deriving a theoretical model for clarifying the dynamics of axial maglev blood pumps. The resonance frequency of the model changed from 73.4 Hz to 34.0 Hz by considering the squeeze effect. The model with the squeeze effect indicates the close resonance frequency of actual maglev blood pump 34.2 Hz. From these result, we judged that the squeeze effect acts significantly on the axial dynamic characteristics of the axial maglev blood pump and the stability of the levitated impeller. Additionally, we showed that the force of squeeze effect has a larger effect on the dynamics of the impeller than viscous damping force and the force of added mass effect.

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In recent years, magnetic wires, which have magnetic properties comparable to those of the electrical steel sheets, have been commercialized and their application to electrical equipment as an iron core is being explored. The conventional electrical steel sheets are generally thin sheets less than 0.5 mm thickness to reduce eddy current losses. The magnetic wires have also small cross-sectional area and can easily processes to be any structure. It is therefore necessary to anneal the magnetic wires after processing to remove residual-strain. However, the conventional heat treatment in an electric furnace is time-consuming and then inefficient. In this study, we paid attention to the current-carrying heating method, in which an electric current is applied directly to the magnetic wires. Due to the Joule loss, effective heat treatment can be therefore performed in a very short time. This paper reports results of a comparative study of magnetic properties of one of the magnetic wires heat-treated by means of the current-carrying heating method.

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Recently, multi-degree-of-freedom spherical actuators are expected to be applied to reduce the size and weight of multi-degree-of-freedom drive systems used in production sites. However, 3-DOF spherical actuators require complicated control because each rotary axis interferes with each other when driving multiple axes simultaneously. Therefore, we proposed a spherical actuator that can control the three axes independently. In this paper, to improve the torque and operating characteristics of the proposed model, the magnetic structure was studied using electromagnetic field analysis by 3D-FEM. The proposed model was studied while separating the driving part in the rotation direction from the driving part in the tilt direction, and achieved a reduction in torque ripple and higher torque during the rotation drive as well as higher torque during the tilt drive.

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We are examining positioning mechanisms that facilitate levitating movement via air films generated by piezoelectric elements (piezo). We have achieved control of levitation height and estimation of levitation height through analyzing the fluctuations in the air film caused by vertical vibrations of the piezo. It has been reported that when a piezo operates at large amplitudes, variations in drive frequency and applied voltage near the resonance frequency can trigger abrupt changes in vibration velocity and current. This phenomenon, known as the "jumping and dropping phenomenon," poses significant challenges. This paper evaluates the vibration and electrical characteristics of the levitation actuator as the drive frequency is varied both discretely and continuously. We aim to clarify the impact of these variations on levitation performance.

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Series elastic actuator consists of an actuator and an elastic component connected in series. One of the applications of SEA is an automatic lettuce harvester that can detect and trace ground surface with contact. The contacting force is controlled to be constant in steady state by position control for regulating the length of the elasticity of SEA. This study focuses on an estimation problem of stiffness of the contacting object when SEA is used in such a tracing application. This paper shows the feasibility of the stiffness estimation via experimental result using extended Kalman filter.

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This study investigates the influence of a dielectric barrier discharge (DBD) plasma actuator using magnetic fluid (MF), termed ”MF-DBD plasma actuator”, on ionic wind velocity. To increase the ionic wind velocity, a multi-MF-DBD plasma actuator is developed by connecting multiple single-MF-DBD plasma actuators in a series, with a parallel electrical circuit. The ionic wind velocity and discharge power of this multi-MF-DBD plasma actuator are measured. The discharge power is measured using the Q-V Lissajous method. It is confirmed that the ionic wind velocity increased with additional lumps of magnetic fluid. Moreover, as the number of MF lumps increases, the discharge power and efficiency also improve. Additionally, this research concluded that when a multi-MF-DBD plasma actuator is put into practical use, it is desirable to increase the number of lumps of magnetic fluid. These results will serve as design guidelines for future research and development of MF-DBD plasma actuators.

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In recent years, the development of plasma actuators has advanced, and applications in various fields are expected. In particular, the development of plasma actuators that utilize the discharge phenomenon from magnetic fluid has made progress. These studies suggest that it is possible to control the ionic wind velocity by changing the shape of the discharge electrode through controlling the magnetic field. In this study, plasma discharge from magnetic fluid is investigated to ascertain whether it is possible to control the discharge direction and wind velocity using a magnetic field. As a result, it is confirmed that the electrode shape can be freely changed using a magnetic field; furthermore, the maximum ionic wind velocity in the vertical direction reaches 0.8 m/s. In addition, the discharge characteristics and power consumption are analyzed and clarified.

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