基于脉冲响应的高强度聚焦超声换能器电阻抗测量方法

高强度聚焦超声(HIFU)换能器是HIFU治疗系统的关键部件,其电阻抗特性是决定各系统参数和换能器工作特性的重要参数。目前采用的阻抗分析仪和频域测量方法成本较高,且难以实现在线测量。为此,对基于脉冲响应的超声换能器电阻抗时域测量方法进行了研究,对测量原理进行了理论分析和仿真验证,并组建了脉冲响应测量实验平台,通过实际测量,比较了脉冲响应法和阻抗分析仪的测量结果,分析了影响测量结果的因素。研究结果表明:在通过电流取样电阻校正和小波去噪后,基于脉冲响应的电阻抗测量方法能取得较高的测量准确度,且测量成本低,可集成于设备实现超声换能器电阻抗的在线测量,为进一步研究高强度聚焦超声换能器的电阻抗特性提供了有力的手段。

Electrical Impedance Measurement Method Based on Impulse Response for High Intensity Focused Ultrasound Transducer

High intensity focused ultrasound transducer(HIFU) is a key part of HIFU therapeutic system,and its electrical impedance characteristics determine the important system parameters and transducer performance.It is difficult to realize online measurement by adopting current impedance analyzer and frequency-domain measurement method.Consequently,we studied the time-domain measurement method for electrical impedance of high intensity focused ultrasound transducer based on impulse response.Firstly,the principle of measurement was theoretically analyzed and verified through simulation.Then,the measurement platform was experimentally established,and the measurement results of impedance analyzer and impulse response method were compared.Finally,the factors affecting the measurement result were analyzed.The results show that,the impulse response measurement method can obtain good measurement accuracy after current sample resistance correcting and wavelet denoising;the measurement method is cost-effective and convenient for integrating in equipment to realize online measurement.This measurement method also provides an effective means of researching electrical impedance characteristic of high intensity focused ultrasound transducer.