A full-to-empty mode controller for the pneumatically-driven blood pump

Presented in this paper is a microprocessor-based controller developed based upon the theory of finite state automata to activate the pneumatically-driven diaphragm blood pump in the full-to-empty mode. Under normal situations, each pumping cycle of the blood pump can be divided into several phases in a proper sequence, and such phase information is contained in the driving air pressure waveform. The controller tries to match the sequential phases with the pressure waveform sampled at real time in an attempt to search for the end-ejection or end-filling of the blood pump. If either the end-ejection or the end-filling can be found, the controller sends triggering signals to the driving unit, and if the sampled pressure waveform can not be matched with the sequential phases or the controller fails to detect the end-ejection or end-filling, the controller activates the driving unit by the parameters of the last measured pumping cycle; thus, the driving unit triggers the blood pump without any stop. The result of laboratory bench tests demonstrates its ability in finding the end-ejection and end-filling points and the reliability of the fail-safe measure.