Transcranial magnetic stimulation is a non-invasive means to stimulate the brain using electromagnetic induction. It has been applied to not only basic science and clinical examinations but also treatments of psychiatric and neurological diseases. We review and present basics and therapeutic application of transcranial magnetic stimulation especially for pain in this paper.

Recently, there has been remarkable progress in the field of magnetic nanoparticles, with them now being applied in cancer surgery. During tumor surgery, lymph node dissection is required along with tumor resection. However, in cases such as breast cancer, lymph node dissection can be omitted if no metastasis is found in the sentinel lymph node (SLN; the first draining lymph node from a primary tumor), thereby reducing postoperative sequelae. The presence or absence of SN metastasis alters the surgical procedure; therefore, intraoperative SLN mapping and rapid pathological SLN diagnosis are required. The standard procedure of SLN mapping is a combination of radioisotope and dye methods, but radioisotope methods have problems associated with regulation and safety. To overcome these problems, a SLN mapping method using magnetic nanoparticles has been developed. This technique has already been clinically applied to breast cancer. In this article, a laparoscopic magnetic probe was developed to expand the SLN theory to visceral organs such as the stomach and gallbladder. A preclinical study of SLN mapping was feasible in laparoscopic minimally invasive surgery. Although resected sentinel lymph nodes can be rapidly diagnosed intraoperatively, the diagnostic accuracy of hematoxylin and eosin staining is limited. Conversely, immunohistochemistry, which gives additional information to pathologists by staining particular proteins, has not yet been used for rapid diagnostics because of the time required for staining. A new rapid immunostaining method is magnetically-promoted rapid immunofluorescence staining using functionalized fluorescent ferrite beads. The antigen-antibody reaction is accelerated by magnetic force, and antigen-antibody complexes can be directly observed with a fluorescence microscope. We have succeeded in diagnosing frozen sections within 15 min from fixation to staining. To realize minimally invasive surgery, a detailed understanding of tumor development is essential, and nanotechnology is being applied in this field to address this issue. In this paper, we introduce a SLN biopsy and rapid immunostaining method based on magnetic nanoparticle technology to further this field.

This paper has proposed a swallowable medical capsule with a magnetically driven biopsy forceps. The biopsy unit is composed of a biopsy forceps and a lead screw actuator with a permanent magnet. When a rotating magnetic field is externally applied, the forceps is projected from a front of the capsule by the lead screw actuator. When the magnetic field is further continuously applied, the forceps is opened at a lesion. Then, by applying the rotating magnetic field reversely, the forceps is closed to collect the tissue and withdrawn into the capsule. This report describes the basic structure, actuation principle and successful operation results by the prototype.

A novel 60 GHz band exposure set-up has been newly developed for studies on thermal thresholds of biological effects of humans exposed to millimeter waves (MMW) that are 5th generation wireless systems (5G) and beyond-5G candidate frequency bands. To achieve high duty exposure to 60 GHz at the desired area, the authors proposed a spatial synthetic beam-type exposure set-up consists of dielectric lens antennas that can irradiate focused beam. We applied orthogonalizing polarized feeding structure to eliminate interference fringes generated in the exposure area due to the combined two-directional beam radiations. Using FDTD simulation, electromagnetic fields distributions on the exposure area due to incident angles of the combined beams was estimated. In order to obtain exposure characteristics, we achieved exposure experiments of temperature rise measurements using a physical arm-shaped skin phantom and human forearm. The developed set-up enabled efficient and desired exposure control for the experiments to explore the biological effects of local exposure to MMWs on human volunteers.

Magnetoencephalographs (MEGs) are highly sensitive to micromagnetic noises, and thus, a high performance magnetically shielded room (MSR) is essential. The shielding effect of a novel MSR should be predicted to verify if it satisfies the required specifications of the MEG at the design stage. Therefore, an accurate prediction method based on the properties of shielding materials and shape of the MSR is necessary. We examined four types of method to estimate µ and to predict the shielding effect. To verify the prediction accuracy, we estimated µ of a permalloy at very small magnetic field strength and predicted the shielding effect of a box-shaped shield, as simple examples, and compared the obtained result with the experimental result. The result of this study shows that some of the prediction methods have an error of less than 70% comparing with the experimental result.

The Blood flow monitoring with wearable devices has been used to detect blood flow disorders. Among various factors such as pulse wave, color, and temperature, this study focused on temperature measurement. In order to confirm the difference in the temperature response of the skin to heat input due to the difference in blood flow rate, we first simulated the temperature distribution of the skin using Pennes’ bioheat conduction equation to see the difference in the calculated temperature response. Next, we conducted animal experiments using a blood flow cutoff model to see the difference in the actual temperature response of the skin. Both the simulations and the animal experiments confirmed the difference in temperature response due to the difference in the amount of blood flow.

Si-containing diamond-like carbon (Si-DLC) thin films have been expected for the coating technique of sliding parts in automobile, since Si-DLC thin films have lower friction coefficient compared with conventional DLC thin films. Plasma-enhanced chemical vapor deposition using tetramethylsilane (TMS) gas has been mainly utilized for the fabrication of Si-DLC thin films. In this article, the mass spectrometric study on Ar-diluted TMS plasmas was performed, and then the influence of the external experimental parameters (i.e., input power and total gas-flow rate) on mass spectrum of the plasmas was examined.

The charging and discharge for insulation materials exposed to the charged particles are the cause of spacecraft operation anomalies. We investigated the space charge distribution of the material during electron beam irradiation using the non-contact type electrode to simulate the space environment. It was observed that the charge accumulation rapidly decreases related to the discharge.

The effect of sheet- and film-type electromagnetic noise suppressors on differential mode (DM) and common mode (CM) transmission characteristics in two parallel lines was investigated. Simple two parallel microstrip lines with a Co-Zr-Nb film were used as a test bench. The transmission characteristics of DM and CM were measured by 4-port network analyzer. The ferromagnetic resonance (FMR) and eddy current losses generated in the Co-Zr-Nb film were calculated by 3D full wave simulator, and the effects of these losses on the transmission characteristics were estimated. The results show that the transmission characteristics are different in DM and CM because the frequency characteristics of the losses are different according to the different FMR frequency in each mode. Furthermore, the feasibility of the application of the magnetic film as a frequency-selective CM filter is demonstrated by using the difference in frequency characteristics of loss of DM and CM.

A measure for analyzing electron energy gain is introduced to seek for desirable conditions for the partial resonance that assists the power deposition to radio-frequency (rf) plasmas driven under confronting divergent magnetic fields. The weight of the solid angle of initial electron release from a source and the effect of electron-molecule collisions are considered in the integration of the expected value of the electron energy.