Intelligent maglev system and its medical application

Abstract

We have developed a magnetic levitation system with an intelligent function. In the system, sinusoidal current is intentionally superposed to electromagnets and the levitating rotor is vibrated. By measuring the phase difference between the displacement of the rotor and current in the electromagnets, the change of the bearing gap and viscosity of working fluid can be detected. The proposed function is applied to the detection of thrombus in a magnetically levitated artificial heart. The experimental results with the porcine blood showed the phase difference increased to two degrees when the thrombus was generated in the pump. Then, the function was further developed for preventing the pump thrombus. By intentionally levitating the impeller with the frequency of 300 Hz and the amplitudes of 2.5 μm, the pump thrombus generated on the impeller was decreased compared with the thrombus without vibration.