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

Introduction

<Fig. 1> Meridians and acupuncture points

<Fig. 2> Eddy current induced by an external magnetic coil

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.

Acupuncture by Magnetic Stimulations

Advantages of Magnetic Acupuncture

The magnetic acupuncture method has some advantages over other acupuncture methods.

Non-invasive ?

Continuously

stimulating ?

Controllability of stimulating

strength

Traditional needle

acupunctureNo No No

Electroacupuncture

No Yes Yes

Magneticacupuncture

Yes Yes Yes

Configuration of the Magnetic Acupuncture System

The system is composed of three major parts.

Magnetic acupuncture probes to generate time-varying magnetic fields

A driving circuit to feed electric current to the probes

A control circuit to generate timing signals

<Fig. 3> The magnetic acupuncture system

Controller & Driver

Probes

To generate very strong magnetic fields up to several tesla, we have used a capacitor charge/discharge technique.

<Fig. 4> The magnetic coil driving circuit

PowerSupply

SwitchingCircuit Driver

TransferCapacitor

DischargeCapacitor

MagneticProbes

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

Graduate School of East-West Medical Science Dept. of Medical Engineering

ProbeCurrent

MagneticProbe

Eddy Current

Acupuncture Point

Design of Magnetic Acupuncture Probes

<Fig. 5> Timing diagrams to control the driving circuit

Maximum pulsing frequency

50 Hz

Maximum voltage of the discharge capacitor

2 kV

Capacitance of the discharge capacitor

100 F

Inductance of the magnetic coils

30 ~ 40 H

Number of pulsing channels

4 channels

<Fig. 6> A photograph of the developed system

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.

<Fig.7> A schematic diagram of the magnetic acupuncture probe

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.

<Fig. 8.> Magnetic flux density produced by the magnetic acupuncture probe

In fig. 9, the magnetic flux densities along the x-axis at several z-values are shown.

<Fig. 9> The magnetic flux densities along the x-axis

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

[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

y

x

z

Graduate School of East-West Medical Science Dept. of Medical Engineering

TransferCapacitorVoltage

DischargeCapacitorVoltage

AcupunctureCoil Current

6kV

2kV

Time

Time

Time

20ms ~ 1s(1Hz ~ 50Hz)200s

250s

2kA

Coil

Magnetic core (=200000)

x

2.5mm 32.5mm 5mm 80mm

10mm

0 1 2 3 4 5 6 7 8 9 100

0.1

0.2

0.3

0.4

0.5

0.6

0.7

x [cm]

B [T]

z = -2mm

z = -5mm

z = -10mm

z

z [cm]