对称结构磁悬浮离心泵心脏辅助装置及流体力学特性

Magnetically Levitated Centrifugal Blood Pump with Symmetric Structure:Hydrodynamic Feature

目的:探讨采用对称设计的磁悬浮离心血泵对血泵抗血栓性的影响。方法:对称结构磁悬浮离心泵由园盘状的泵壳,入口管,电机定子,转子-叶轮体构成,转子-叶轮体中包埋两套经向永磁悬浮磁环及轴向控制永磁体。转子-叶轮体采用四极无刷直流电机的驱动方式。入口管外包绕轴向绕组并与轴向控制永磁体相对,馈电时可保持转子-叶轮体的轴向位置。该轴向电磁控制系统采用霍尔信号及反馈控制装置。本文样机最大直径45mm,总长度75mm,总重量210g。所有血液接触面均采用钛合金加工制作。对称结构磁悬浮离心泵在体外模拟循环台进行流体力学特性测试。结果:实现转子-叶轮体的全悬浮需要约2.1W的能耗。悬浮功率还受到泵的重力姿态影响,变化姿态可导致约±0.5W的功率波动。体外模拟实验显示血泵可在6000r/min的转速条件下产生5L/min和100 mm Hg压力的流体输出,能满足左心辅助的需求。改变转子-叶轮体的旋转方向对流体输出特性没有影响,与预想的特性一致。结论:对称结构磁悬浮离心泵流体力学特性可满足左心辅助需要。悬浮耗能虽受重力影响,但可以实现转子-叶轮体全悬浮。流体力学特性在改变旋转方向条件下不变,转子-叶轮体交替旋转的驱动策略可行。

Objective： To explore the effect of symmetrical design of magnetic suspension centrifugal blood pump on antithrombotic effect of blood pump. Methods： The prototype of SCBP is composed of a pump house in disk shape with a conductive inlet tube, a motor stator and a rotor-impeller assemblage set, including two sets of permanent magnetic bearing ring for radial suspension as well as an axial-control magnet. The rotor-impeller assemblage is actuated by a 4-pole brushless DC motor. An axial coil surrounds around the conductive inlet tube, facing the axial-control magnet inside the rotor-impeller assemblage. The electric current through the axial coil could keep the axial position of the rotor-impeller assemblage. This active system uses feed-back mechanism and Hall sensor to detect the axial position of the rotor. The prototype of SCBP in this study is 45 mm in largest width and in a total length of 75 mm, with a weight of 210 grams,all the contact surface is made of titanium alloy. A mock circulation was set up for evaluating the hydrodynamic feature of the prototype of SCBP. Results：In vitro study shows that the energy for suspension of the rotor-impeller is about 2.1W. The suspension power is slightly affected by the pump gesture, with a ±0.5W fluctuation. The tests in the mock circulation suggest that the SCBP is excellent of hydrodynamic characteristics, producing output of 5L/min against the pressure of 100 mm Hg, at 6000r/min which is enough for left ventricular assistance. Such a flow output is not affected by the change of rotational direction, as prefigured. Conclusion：The SCBP produce enough hydrodynamic output for LVAD. Although the alteration of gravitation force would slightly increase the suspending power decrease but the rotor is kept fully levitated. Hydrodynamic output was not affected by change of rotational direction of the suspended rotor-impeller. The driving strategy of impeller rotation alternatively both in clockwise direction or anticlockwise might be feasible.