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Studies of cardiovascular system and cardiac assistance devices are key research direction in our laboratory, a challenging project requires conducting physiological experiments on animal constantly. In an operation, It is significant to detect small changes in important physiological parameters for ensuring the integrity of animal. As a result, in order to detect and acquire accurate parameter variation, a simple monitoring module is quite required as an adjunct to experiments. Directing the widely applied invasive blood pressure monitoring system, a typical block of it is introduced here. Sensor of this system applied has been used in present medical field whose superiorities embody in its continuity, high sensitivity and hygiene. A simulated experiment was established to functionally calibrate the performance of this module to ensure signals can be recorded by the data acquisition system. The result showed a high linear correlationship between pressure and output. That the serial output can be used to interface to a computer for further analysis serves a function as continuous monitor during experiment.

Miniature axial flow pump (M-AFP) is a ventricular assist device that supports the failing ventricle in advanced stage heart failure. In the past several years, we have developed two types of M-AFP aiming for children. In this paper, mechanical performance of them are tested and analyzed in order to help us find out their differences in nature. A simulative circulative apparatus is designed that can be used to quantitatively predict the mechanical characteristic parameters of the pumps and their relationship. Under the condition of load pressure invariance, we mainly test the change of blood flow with these two pumps respectively. The type A has a volume of 47ml; with external diameter of 26mm and length of 72mm. The simulative cardiac flow attains 3–4L/min under the pressure of 100mmHg, which is enough to assist the left ventricular of children. In all the two pumps, rotate speed of impeller and flow rate of blood present positive mutuality with pressure invariance. Besides, comparing with type A, the type B has smaller volume, and it is much easier for type B to increase rotate speed of the pump and comparably reduce energy consumption. Apart from the characters of smaller volume and simpler configuration, the output of miniature axial blood pump has achieved required pressure and blood flow. We still have the possibility to improve the blood pump by reducing energy consumption and increasing efficiency. The performance test and comparison in simulative circulation apparatus that is out of body is very important for improvement of blood pump. It can accelerate the development of mechanical assistant therapy and increase the cure rate of heart failure for children.

Objective: This paper introduces a comparable optimized PWM ML4428 control chip, which provides all the functions necessary for controlling a Blood Pump. The Blood Pump is based on an Active magnetic Bearing (AMB) system. Methodology: Directing to the dual-loop speed control system in the chip, which has a confined range of speed-modulate voltage, A speed-modulate design is introduced for the purpose of allowing off-range modulate voltages to work. This module serves a function that can transform the off-range modulate voltage into within-range modulate voltage through a digital electrical network as an AD converter to implement PWM.