IEEE Trans Ultrason Ferroelectr Freq Control. 2020 Aug;67(8):1620-1631. doi: 10.1109/TUFFC.2020.2978234. Epub 2020 Mar 4.
This research presents double-parabolic-reflector wave-guided ultrasonic transducers in order to realize wideband (0-2.5 MHz), multiharmonic mode excitations (over 20 modes), and to obtain large mechanical/acoustic outputs. The double-parabolic-reflector mechanism serves as a horn structure at low frequencies and acoustic-focusing structure at high frequencies to enhance the energy density of the incident ultrasound. Upon combining simulation and experimental methods, we examined and verified the basic performance and working mechanisms of the double-parabolic-reflector waveguides: multimode excitation belongs to the harmonic modes from the thin waveguide. At the megahertz range near the thickness mode of the piezoelectric element (PZT), energy density of the incident ultrasound is enhanced by double-parabolic reflections, and the amplification ranges 10 to 40× between 1 and 2.5 MHz. At burst excitations, the amplification performance is independent of the length of the thin waveguide. Compared with conventional Langevin transducers and high-intensity focused ultrasound (HIFU) transducers, our transducers possess a wide working frequency with large mechanical/acoustic outputs and large vibration velocity amplification. By introducing these new features, our proposed method is a promising candidate for examining basic physics parameters, such as frequency dependence, in the fields of medicine, biology, industry, etc.
本研究提出了双抛物面反射器波导超声换能器，旨在实现宽带（0-2.5MHz）、多谐模式激励（超过 20 种模式），并获得大的机械/声输出。双抛物面反射器机制在低频下作为喇叭结构，在高频下作为声聚焦结构，以增强入射超声的能量密度。通过结合模拟和实验方法，我们检验和验证了双抛物面波导的基本性能和工作机制：多模激励属于薄波导的谐波模式。在接近压电元件（PZT）厚度模式的兆赫兹范围内，通过双抛物面反射增强了入射超声的能量密度，在 1 到 2.5MHz 之间的放大范围为 10 到 40 倍。在突发激励下，薄波导的长度对放大性能没有影响。与传统兰杰文换能器和高强度聚焦超声（HIFU）换能器相比，我们的换能器具有宽工作频率、大机械/声输出和大振动速度放大的特点。通过引入这些新特性，我们提出的方法有望成为研究医学、生物学、工业等领域的频率相关等基础物理参数的候选方法。
