Design, Simulation And Experimental Investigation Of The Magnetic Stimulation Analgesic System Specific To The Spinal Cord

With the development of society, the tendency toward an aging time looms in our country. The problem of aging becomes increasingly prominent and the pain originating form age-related diseases emerges as a common issue faced by humans. The existing therapies consisting of drug treatment and invasive surgical methods may produce side effects on patients more or less, especially on the senile ones. This research proposed a new analgesic theory based on the mature technology of transcranial magnetic stimulation:the technology of the magnetic stimulation analgesic system specific to the spinal cord, which can restrain or block the transmission of the pain signals by means of applying magnetic pulses beneath the spinal cord. Considering the effectiveness and non-invasiveness of this technology, it has promising applications in the treatment and investigation of age-related diseases.Based on the software of Pspice, we built the magnetic stimulation system to simulate the work state of the circuits and to determine all the needed parameters. The simulation results determine that the capacitance value is 250 μF, the resistance value is 0.1 Ω, the inductance value is 20 μH and the optimal working state of the circuit is underdamping. On the first step, a small-voltage magnetic stimulation experimental system was built. The distribution of the magnetic field in the space produced by the figure-of-eight coil in this small-voltage system was measured. The results of the measurement shows that along the x axis the distribution of the magnetic field emerges a main peak at the origin and two symmetrical deputy peaks on both side of the origin. The ratio between the deputy peak value and the main peak value is 1/2. On y axis and z axis, the magnetic field value decreases symmetrically from the origin to both end of the axis. A custom-designed apparatus was used to measure the electrical filed produce by the figure of eight coil in the artificial tissue fluid at the same points where the main peak and deputy peaks emerge. The measurement results show that the ratio between the electrical field value at the main peak point and that at the deputy peak point. We also tested whether the magnetic field can be attenuated by the skin and bone when it passes thorough them. The statistical comparisons show that the p value is bigger than 0.05 and no significant differences are observed. This thus suggests that the attenuating effects of the skin and bone are not significant.On the foundation of the small-voltage magnetic stimulation experimental system, the high-voltage magnetic stimulation working system was built. We measured the magnetic field and the electrical field induced by the figure of eight coil of the high-voltage working system, and found that the high-voltage magnetic field distribution patterns along x, y and z axis resemble their small-voltage counterparts. But the magnitude of the magnetic field and electrical filed induced by the working system increased markedly. In this research when the voltage is increased by eight times, the magnetic field is consequently strengthened by x times. In z axis, at the point away from the original point x cm, the increment of the magnetic field enables the effective stimulation depth of the coil to augment significantly.