Recently, a high intensity focused ultrasound (HIFU) is drawing a lot of attention from medical and non-medical fields due to its potential for extreme high pressure levels as well as ultra high spatial resolution. At the heart of every HIFU system is a focused ultrasound transducer, and its electrical and acoustic properties play a key role. During the transducer design phase, it is important to quickly obtain the electrical and acoustic parameters corresponding to the transducer structure. Currently, researchers mainly use finite element methods for simulation, but by doing so they lose the deeper insight into the key aspects of the complex electro-acoustic interaction between the transducer, the electric matching network and the front and back acoustic load. A theoretical model based on the Krimholtz-Leedom-Matthaei (KLM) approach of a focused acoustic source is presented. The model includes the impact of the dielectric and mechanical losses and allows for evaluation of the performance of the transducer in terms of electro-acoustic efficiency. The theoretical performance and the impact of the included loss mechanisms on it is calculated up to 9 harmonic resonance frequency. The model is verified using test transducers operating at 4 MHz (fundamental), 12 MHz (3 harmonic) and 20 MHz (5 harmonic) resonance frequencies. Both the predicted input impedance and predicted electro-acoustic efficiency exhibit very good agreement with the experimental data. An effective material and device parameter identification method based on multi-dimensional minimization algorithm is presented, as well. The results can be directly applied to optimization and development of high-frequency focused acoustic sources taking advantage of the high focusing gain and very high spatial resolution.

中文翻译：

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谐波驱动聚焦声源的分析建模并进行实验验证

近年来，高强度聚焦超声（HIFU）因其具有极高压力水平和超高空间分辨率的潜力而受到医学和非医学领域的广泛关注。每个 HIFU 系统的核心都是聚焦超声换能器，其电学和声学特性起着关键作用。在换能器设计阶段，快速获得与换能器结构相对应的电学和声学参数非常重要。目前，研究人员主要采用有限元方法进行仿真，但这样做却无法深入了解换能器、电匹配网络以及前后声负载之间复杂电声相互作用的关键方面。提出了基于聚焦声源的 Krimholtz-Leedom-Matthaei (KLM) 方法的理论模型。该模型包括介电和机械损耗的影响，并允许评估换能器在电声效率方面的性能。理论性能和所包含的损耗机制对其的影响计算至 9 个谐波谐振频率。该模型使用在 4 MHz（基波）、12 MHz（3 个谐波）和 20 MHz（5 个谐波）谐振频率下运行的测试传感器进行验证。预测的输入阻抗和预测的电声效率都与实验数据非常吻合。还提出了一种基于多维最小化算法的有效材料和器件参数识别方法。研究结果可直接应用于利用高聚焦增益和极高空间分辨率的高频聚焦声源的优化和开发。