Development Of A Magnetic Stimulation System

Magnetic stimulation is a form of physical stimulation,stimulating excitable tissue with an electric current induced by an external time-varying field.With the developing of electromagnetism and advance of electronic technology, magnetic stimulation has been testified a safe and efficient modern medical method and widely applied in clinic and research fields. Magnetic stimulation was originally used in stimulating central and peripheral nerve tissue. Following the promotion of magnetic field and incretion of stimulation frequency, application range of magnetic stimulation expands constantly by the exploration of clinicians and researchers from various realms. Recently, some reports appear about magnetic stimulation applied in some other tissues and organs such as muscle, skeleton, kidney and cardio. The employment of magnetic stimulation covers diagnosis, therapy and prognosis. While magnetic stimulation application range enlarges, clinic utility asks for the advancement and improvement of magnetic stimulator, which is the key issue to expand application of magnetic stimulation.For expounding of the design of the magnetic stimulation, the principle of magnetic stimulator and stimulation mechanism is introduced firstly. Charging electric energy in a capacitor and discharging the energy into a coil, current pulse flows through the coil inducing a magnetic field pulse. Magnetic field traversing tissue or organs will excite induced electric field and induced current in tissue or organs.Based on the principle and mechanism, a whole solution of the magnetic stimulation system is drawn out. The system is illuminated from charging loop, discharging loop and control circuit. Because instability and low-efficiency is the two main drawbacks of magnetic stimulator, soft-switch technology is adopted in the charging loop and reverse absorbing circuit is added into the discharging loop to develop the stability and efficiency.At the same time, controlling the synchronization of charging and discharging will help the system run stably. A single-chip microcontroller unit is adopted in the system to fulfill adjusting the magnetic field from 0.5Tesla to 1Tesla, selecting the stimulating frequency from 0.5Hz to 10Hz and setting up stimulation time previous or counting the time after starting stimulation and triggering a single stimulation pulse.At the end of the thesis, the characteristics of the magnetic field and induced electric field are discussed from theoretic analysis, measurement and calculation, the effective of the output magnetic field stimulation and the fulfilling of the pre-targets is considered.