Tadakuni Sato

A new contactless power-signal transmission device for implanted functional electrical stimulation (FES)

This paper proposes a new contactless power-signal transmission device using electromagnetic coupling for a functional electrical stimulation system, which consists of two coils. With the primary coil outside and the secondary inside the body, the in-vivo coil composed of a coupling of two parts, one to receive power and one to receive signal, each at a different radio frequency. In this study, our approach is based on a structure to implement a simultaneous power-signal transmission system, which enables power and signal for muscle stimulation to be concurrently transferred from outside the body, while allowing for the separation inside. Moreover, the induced voltage of the magnetic flux on signal transmission, suppressed to 0.15 V, the output signal voltage of 2 V or more was established at a signal frequency of 7.7 MHz, thus leading to stable operation. The study also aimed to reach for higher power output of the secondary coil.

Construction of non-contacting power feeding system to underwater vehicle utilizing electro magnetic induction

As a method of sending electric power to underwater vehicles, the contactless power supply system (CLPS) utilizing electromagnetic induction is proposed. We also developed the cone-type coil that is suitable for use underwater. This system has an efficient nature and high power transmission capability, even when fluctuation in the sea exists. Furthermore, the electromagnetic force generated during power transmission will be useful for maintaining the location of an underwater vehicle stably. If this system is applied to the vehicle, the restriction of a sphere of activity and time in inquiry is obtained. So it is possible to reduce costs. In this paper, we considered water cooling and it is confirmed possible to transmit about 1 kW of electric power at about 90% efficiency when the diameter of the coil is 48 mm. We also designed the coil size which is suitable for the specification of the battery on the real vehicle.

Consideration of handy excitation apparatus for the inductive hyperthermia

Hyperthermia is one of the therapeutic techniques for cancer that attempts to necrotize cancer cells by heating. In this study, we examine a device based on handy circular excitation coils and hybrid heaters for high-temperature hyperthermia using the soft heating method.

Heat characteristics of micro magnetic heat elements for advanced hyperthermia

Hyperthermia is one of the therapeutic techniques that attempt to mainly induce necrosis in cancer cells by heating. To cause necrosis in tumors under hyperthermia with certainty, the authors proposed high-temperature hyperthermia. For this study, the authors examined the heat characteristics of the heat element composed of a thermosensitive magnetic material and a metal ring with various volumes. Our results showed that heat characteristics have a tendency to saturate with an increase in element volume.

Synchronous rectification for contactless power supply utilizing Mn–Zn ferrite core coils

Contactless power supply systems transmit electric power by electromagnetic induction with a pair of coils. The efficiency and the output voltage depend on parameters of coils. We studied the best parameter values that realize stable high efficiency contactless power supply. In the application with low output voltage, the voltage drop of the diodes becomes dominant power loss. A synchronous rectification was proposed as a solution of this problem. Our contactless power supply system for an artificial heart operates at 190kHz. We use planar coils with Mn–Zn ferrite cores. Highly stable output voltage and 88% maximum efficiency were realized.

Magnetic nondestructive detection of cracks in a distribution line

An important problem in the electric power industry is the degradation of distribution lines. We propose a nondestructive detection system for cracks in a distribution line by measuring the magnetic field around the distribution line when it is energized. In this paper, we examine the distribution of the magnetic field around a 50 Hz distribution line in a laboratory experiment. From our observations, we develop and refine an algorithm for detecting cracks by using the magnetic field direction.

Thermotherapy with metallic stent heated by external magnetic excitation

Stents are one method of treatment for stenosis of lumens organ from various causes. The cylindrical metallic stents are composed of alloy wire. After stents are implanted, however, the stenosis may recur due to a tumor or abscess again. It is particularly difficult to remove tumors or abscesses of the bile duct by surgical repair, because the duct is in a deep portion of the abdomen. We propose a noninvasive remedying method for tumors and abscesses by using thermotherapy with magnetically excited metallic stents. Currently, commercialized stents are not manufactured to allow for heating. In this paper, we studied the feasibility to heat the stents by external magnetic excitation for thermotherapeutic applications.

Temperature control of SMA artificial anal sphincter

In this article we used artificial sphincter utilising shape memory alloy (SMA) which consists of Ni and Ti. The anal canal is placed in between two boards fabricated from SMA. Because the form of SMA changes towards temperature, the flexure of the SMA boards in response to being heated by flexible heaters stuck on these boards effects opening anal canal.

New functional electrical system using magnetic coils for power transmission and control signal detection

In order to improve the Functional Electrical Stimulation system, we considered new methods of power transmission to the electrodes and control of the system. Concerning power transmission, a method is proposed to directly supply electric power to the electrodes by magnetic coupling without the use of electric wires. Selective power transmission to two electrodes is studied experimentally. Power transmissions at frequencies of 96 kHz and 387 kHz are sent separately to secondary circuits, and about 5 electrodes can be used. Concerning control of the system, a new control method that uses auricular movements is proposed. The effect of electrical stimulation is examined in the process of acquiring voluntary auricular movement. The acquisition method along with biofeedback or functional electrical stimulation is effective to some extent.

Hyperthermia Implant Consisting of Resonant Circuit Delivered to Tumor Through 18 G Needle

A resonant circuit is expected to be used as a heating source for hyperthermia implants, because the circuit can be effectively heated by an applied ac magnetic field. In order to realize a less invasive delivery of the implant through a catheter or injection needle, its miniaturization down to 1 mm or less is essential. However, the heating temperature of the resonant circuit is reduced by downsizing of the size of the circuit. A ferrite core in a coil is employed in order to obtain higher induced voltage in the inductor, resulting in the higher temperature rise of the resonant circuit. The resonant circuit implant consisting of the core coil has been prepared. Its diameter is 0.9 mm and the implant can be delivered through an 18 G needle.