In this paper, the cavitation characteristics of centrifugal blood pumps under variable speeds were studied by using ANSYS-CFX and MATLAB software. The study proposed a multi-scale model of the “centrifugal blood pump—left heart blood circulation”, and analyzed the cavitation characteristics of the centrifugal blood pump. The results showed that the cavitation in the impeller first appeared near the hub at the inlet of the impeller. As the inlet pressure decreased, the cavitation gradually strengthened and the bubbles gradually developed in the outlet of the impeller. The cavitation intensity increased with the increase of impeller speed. The curve of the variable speeds of the centrifugal blood pump in the optimal auxiliary state was obtained, which could effectively improve the aortic pressure and flow. In variable speeds, due to the high aortic flow and pressure during the ejection period, the sharp increases in speeds led to cavitation. The results could provide a guidance for the optimal design of the centrifugal blood pump.

Because of their high power density and compact size, permanent-magnet (PM) motors have been commonly used to drive rotary blood pumps (RBPs), which are focused on the treatment of end-stage heart failure or as the bridge to a heart transplant. In this paper, a bearingless PM motor has been proposed for axial blood pump applications. The finite-element method (FEM) is used to predict the electromagnetic characteristics of the designed motor with improved performance. Two topologies are investigated, namely the integral-slot and distributed-windings method and the fractional-slot and double-layer concentrated windings method. Both motors are analyzed and optimized. FEM reveals that, compared with the integralslot motor, the fractional-slot motor offers significantly enhanced performance, including reduced cogging torque, improved back electromotive force (back EMF), and decreased magnetic flux leakage. Finally, hydraulic experiments have been conducted in a mock-circulation loop to validate the feasibility of the designed motor for an axial blood pump. The results show that the fractional-slot bearingless PM motor can drive the RBP to produce physiological blood flow with reasonable efficiency.

In this paper, a new high reliability linear drive device, termed as stator-permanent-magnet tubular oscillating actuator (SPM-TOA), is proposed for artificial hearts (AHs). The key is to incorporate the concept of two independent phases into this linear AH device, hence achieving high reliability operation. The fault-tolerant teeth are employed to provide the desired decoupling phases in magnetic circuit. Also, as the magnets and the coils are located in the stator, the proposed SPM-TOA takes the definite advantages of robust mover and direct-drive capability. By using the time-stepping finite element method, the electromagnetic characteristics of the proposed SPM-TOA are analyzed, including magnetic field distributions, flux linkages, back- electromotive forces (back-EMFs) self- and mutual inductances, as well as cogging and thrust forces. The results confirm that the proposed SPM-TOA meets the dimension, weight, and force requirements of the AH drive device.

No abstract

The invasive model of power supply for the commercial blood pumps has brought great discomfort to the patients. An inductive power transmission system based on transformer for blood pumps has been designed and developed. The system is mainly consist of power supply, control circuit of switch, transformer, rectifier circuit and energy storage element. Experiments on power transmission in the system have been conducted for evaluation impact of frequnency of switch, gas gap and windings number on the transmission efficiency of the system. The experimental results demonstrate that frequency of switch, gas gap and windings number influence the transmission efficiency in the inductive power supply system. The transmission efficiency decreases with the increase of the gap in the transformer and the system with the gap of 1 mm has the highest efficiency in the same performance conditions. The relation between the efficiency and the frequency of switch or the secondary windings number seem to be an approximate normal distribution: the system with the secondary windings number of 60 has the maximal efficiency; when the frequency of switch is 40 kHz, the efficiency reaches the peak.