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基于双频超声换能器的双端动态电阻抗匹配方法研究

Study on Dual-End Dynamic Electrical Impedance Matching Method for Dual-Frequency Ultrasound Transducers

  • 摘要: 双频超声换能器作为双频超声成像技术的核心元件,通过发射和接收两种不同频率的信号来兼顾成像深度和成像分辨率,电阻抗匹配对信号的发射和接收都至关重要。然而,现有的电阻抗匹配研究大多聚焦于工作在单一频率下的超声换能器的发射或接收,无法同时实现双频超声换能器在发射和接收中的宽频匹配。本文提出一种双端动态电阻抗匹配方法,专为使用不同振型来实现双频的收发型超声换能器设计。该方法借助双通道选通机制实现互不干扰的发射/接收双端匹配,支持网络拓扑与元件参数的灵活切换,并采用Nelder-Mead单纯形法进行元件参数的快速计算。实验结果表明,双端动态电阻抗匹配方法显著提升了双频带的回波电压峰峰值和−6 dB带宽以及成像信噪比,10 MHz频带分别提高了31.9%、29.6%和14.8%,30 MHz频带分别提高37.7%、49.0%和21.4%。这一方法显著提高了超声换能器在不同工作频率下的成像性能,对促进双频超声成像技术的发展具有重要价值。

     

    Abstract: Dual-frequency ultrasound transducers, as a core component of dual-frequency ultrasound imaging technology, usethe transmission and reception of two different frequency signals to optimiseimaging depth and resolution. Electrical impedance matching iscrucial for signal transmission and reception. However, existing studies on electrical impedance matching primarily focus on the transmission or reception of ultrasound transducersat a single frequency, failing to achieve broadband matching for dual-frequency transducers during both transmission and reception. This paper proposes a dual-end dynamic electrical impedance matching method for transmitting and receiving ultrasound transducersthat achieve dual frequencies by using different vibration modes. This method employs a dual-channel gating mechanism to achieve dual-end matching for transmission and receptionwithout mutual interference. It supports flexible network topology switchingand component parameters, and uses the Nelder-Mead simplex method for rapid calculation of component parameters. Experimental results demonstrate that the dual-end dynamic electrical impedance matching method significantly enhances the peak-to-peak voltage (Vpp) and −6 dB bandwidth of echoes and imaging signal-to-noise ratio (RSN) across dual-frequency bands. In the 10 MHz band, the Vpp, −6 dB bandwidth, and RSN improved by31.9%, 29.6%, and 14.8%, respectively, while in the 30 MHz band, these values increased by 37.7 %, 49.0 %, and 21.4 %. This method significantly improves the imaging performance of ultrasound transducers at different operating frequencies, providing important support for the advancement of dual-frequency ultrasound imaging technology.

     

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