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Dept. of Medical Engineering Graduate School of East-West Medical Science Introduction Acupuncture by Magnetic Stimulations Acupuncture, a major treatment method in TCM(Traditional Chinese Medicine), becomes an alternative method for treating pains in western medicine. Electro-acupuncture techniques have been widely used in TCM for more efficient treatments. Acupuncture needles, essential tools for both traditional and electro acupunctures, are very invasive and occasionally unacceptable to very weak patients or children. We introduce a magnetic acupuncture system with which needle-less acupuncture therapy can be performed By applying a very strong magnetic pulse at the vicinity of the human skin, we can induce electric current inside the human body. The induced eddy current has been utilized to stimulate central or peripheral nerves in western medicine.[1] By using specially designed stimulating coils, we can stimulate acupuncture (meridian) points in a non-invasive manner. Advantages of Magnetic Acupuncture The magnetic acupuncture method has some advantages over other acupuncture methods. NonContinuously invasive ? stimulating ? <Fig. 1> Meridians and acupuncture points Probe Current Magnetic Probe Probes <Fig. 3> The magnetic acupuncture system To generate very strong magnetic fields up to several tesla, we have used a capacitor charge/discharge technique. Power Supply Magnetic Probes Controllability of stimulating strength Transfer Capacitor Traditional needle acupuncture No Electro acupuncture No No Discharge Capacitor No Switching Circuit Driver Yes Yes <Fig. 4> The magnetic coil driving circuit Magnetic acupuncture Yes Yes Yes Eddy Current Configuration of the Magnetic Acupuncture System Acupuncture Point The system is composed of three major parts. Magnetic acupuncture probes to generate time-varying magnetic fields <Fig. 2> Eddy current induced by an external magnetic coil Controller & Driver A driving circuit to feed electric current to the probes A control circuit to generate timing signals To feed electric current into discharge capacitors with a small capacity power supply, we have used transfer capacitors. During non-stimulating intervals, the power supply charges the transfer capacitors. After then, the electric charge is transferred to the discharge capacitors.(See fig.5) After multiple charge transfers from the transfer capacitors to the discharge capacitors, the voltage of the discharge capacitor rises up to 2 KV. The switching components are high speed SCRs Dept. of Medical Engineering Graduate School of East-West Medical Science Design of Magnetic Acupuncture Probes 6kV Transfer Capacitor Voltage 250ms Time 2kV Discharge Capacitor Voltage 200ms 20ms ~ 1s Time (1Hz ~ 50Hz) 2kA Acupuncture Coil Current To stimulate acupuncture points efficiently, small sized loop coils are preferable. It is very difficult to cool the small sized loop coils. In this study, we have used a large loop coil with a magnetic core along the central axis of the loop coil, as shown in fig. 7. In fig. 9, the magnetic flux densities along the x-axis at several z-values are shown. 0.7 B [T] 0.6 z = -2mm 0.5 0.4 z = -5mm 0.3 0.2 0.1 z z Time 0 y Magnetic core (m=20000m0) <Fig. 5> Timing diagrams to control the driving circuit Coil 2.5mm 32.5mm 5mm z = -10mm 0 1 2 3 4 5 6 7 8 9 10 x [cm] x <Fig. 9> The magnetic flux densities along the x-axis 80mm Maximum pulsing frequency x 10mm 50 Hz Maximum voltage of the discharge capacitor 2 kV Capacitance of the discharge capacitor <Fig.7> A schematic diagram of the magnetic acupuncture probe 100 mF Inductance of the magnetic coils 30 ~ 40 mH Number of pulsing channels 4 channels Using a commercial FEM tool, we have analyzed the spatial distribution of the magnetic field produced by the magnetic acupuncture probe. In fig. 8, the magnetic flux density of the probe is shown. z [cm] Conclusions The developed magnetic acupuncture system gives the localized stimulation similarly to the conventional electro acupuncture. Clinical tests will be performed very soon in a Korean traditional medicine hospital and a Chinese traditional medicine hospital. The magnetic acupuncture system is expected to become a complementary tool to the conventional acupuncture techniques. References <Fig. 6> A photograph of the developed system <Fig. 8.> Magnetic flux density produced by the magnetic acupuncture probe [1] M.J.R. Polson, A.T. Barker, and I.L. Freeston, "Stimulation of nerve trunks with time varying magnetic fields", Med. Biol. Eng. Comput., Vol. 20, pp.243-244, 1982