Time domain electrical impedance measurement method for ultrasound transducer

High intensity focused ultrasound transducer (HIFU) is a key part of HIFU treatment system, the electrical impedance characteristics of which is an important parameter. The currently adopted electrical impedance measurement methods are based on frequency-domain, which are expensive and difficult to realize on-line measurement. The time-domain measurement method for electrical impedance of high intensity focused ultrasound transducer based on impulse response is studied in this paper. The principle of measurement is theoretically analyzed and verified through simulation. The measurement platform is experimentally established and the measurement results of impedance analyzer and impulse response method are compared. The approaches of current sampling resistor correction and wavelet denoising to reducing measurement error are presented. The study 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 on-line measurement. This measurement method also provides an effective means of researching electrical impedance characteristic of high intensity focused ultrasound transducer.