基于FPGA的血管内超声增强溶栓激励系统的设计

Design of Intravascular Ultrasound-enhanced Thrombolysis Excitation System Based on FPGA

设计了一种基于FPGA(ZYNQ-7Z020)的频率、幅值和占空比可调的血管内超声增强溶栓激励系统。首先FPGA基于直接数字频率合成技术(DDS)产生波形幅度二进制数据,然后通过外接的子卡,包括D/A转换电路、有源低通滤波器、功率放大电路和阻抗匹配电路等,实现脉冲串信号的输出。经过测试,此系统输出的波形达到设定目标,具有实现简单,控制灵活等优点,经过电阻抗匹配后超声换能器输出的峰值负压提高一倍。采用离体血栓模型对该系统进行验证,结果表明产生的超声空化效应能加速尿激酶的渗透,使得溶栓率提高20%左右。

An intravascular ultrasound-enhanced thrombolysis excitation system with adjustable frequency, amplitude and duty cycle was designed based on FPGA(ZYNQ-7 Z020). Firstly, the FPGA generated waveform amplitude binary data based on direct digital frequency synthesis(DDS) technology, and then the data was converted into burst signal through an external daughter card, which included D/A conversion circuit, active low-pass filter, power amplifier circuit and impedance matching circuit. The test results demonstrated that the output waveform reached the target with advantages of simple implementation and flexible control, the peak negative pressure generated from ultrasound transducer was doubled by means of an electrical impedance matching network. In vitro thrombus models were applied to verify the excitation system, it turned out that ultrasound cavitation effect generated could accelerate the penetration of urokinase and increase the thrombolysis rate by about 20%.