Study Of Pulse Wave Doppler Blood Flow Meter Based On FPGA

This thesis is sponsored by National Natural Science Foundation of China"The Basic Research of Compression Cardiac Assist Devices Using Ultrasonic Flexible Actuators". The blood velocity of aorta is one of the most important parameters, not only for the performance evaluation but also for the control of cardiac compression assist devices. The purpose of this thesis is to develop a flow meter, which is non-invasive and miniature. What's more, this flow meter can measure blood velocity of aorta on the desired distance quickly, which can provide infromation about thrombolic event.The thesis aims to study object and extract the blood flow parameters of aorta. According to the principle of pulse wave (PW) Doppler, a PW Doppler blood flow meter was designed, which is used to detect blood flow in the aorta. According to the practical function, the system was divided into two parts: the analog part which consists of ultrasonic emitting circuits, ultrasonic receiving circuits and their switcher, and the digital part which is used to extract blood velocity information from the frequency difference, which is demodulated from echo signal acquisition. ALTERA CYCLONE II EP2C20F484C7N is the digital signal processor in this part. This design takes advantage of its high speed feature to improve real-time parallel performance of this system and its time series feature to control the external component. What's more, this design adopts the method of separating the analog circuit and the digital circuit which can improve the stability and reliability of the system.The pulse wave Doppler blood flow meter designed in this thesis can measure blood flow velocity from a specified point in the aorta,and this result is very important to evaluate performance of the direct cardiac compression assist.