Biomedical Engineering Department, Tulane University, Lindy Boggs Center, Suite 500, New Orleans, Louisiana 70118, USA.
J Acoust Soc Am. 2012 Sep;132(3):1368-77. doi: 10.1121/1.4740483.
Properties of a piezoelectric polymeric angioplasty balloon that may decrease the problems of acute closure and restenosis are evaluated in this study. Polyvinylidene difluoride (PVDF), a piezoelectric and pyroelectric polymer, has sufficient strength to serve as a standard angioplasty balloon as well as functioning as an ultrasonic transmitter and/or receiver. These properties enable potential therapeutic applications using ultrasound such as plaque ablation and sonotherapy as well as vulnerable plaque diagnosis using thermography. This study investigates the resonant structure of the PVDF balloon catheter in the frequency range 5-100 kHz. Vibrations of the piezoelectric balloon are modeled using cylindrical shell theory and compared with the observed modal frequencies of PVDF cylinders with and without internal pressure. Modal frequencies are determined by measuring the near-field pressure response of the PVDF cylinders using a high frequency microphone. A rich nodal structure is observed between 5 and 100 kHz with peak relative amplitudes measured between 42 and 45 kHz. Higher order modes for cylinders with 9 μm and 28 μm wall thickness increase in frequency as the internal pressure is increased. Experimental measurements confirm theoretical models that predict both pressure-dependent and pressure-independent resonant frequencies. Frequencies of pressure-dependent modes are calculated within 2.2% of measured values at high pressure.
本研究评估了一种压电聚合物血管成形球囊的特性，这些特性可能会降低急性闭塞和再狭窄的问题。聚偏二氟乙烯（PVDF）是一种压电和热释电聚合物，具有足够的强度，可以用作标准的血管成形球囊，也可以用作超声发射器和/或接收器。这些特性使使用超声进行潜在的治疗应用成为可能，如斑块消融和超声治疗，以及使用热成像进行易损斑块诊断。本研究在 5-100 kHz 的频率范围内研究了 PVDF 气球导管的谐振结构。使用圆柱壳理论对压电气球的振动进行建模，并将其与带有和不带有内压的 PVDF 圆柱的观察到的模态频率进行比较。模态频率通过使用高频麦克风测量 PVDF 圆柱的近场压力响应来确定。在 5-100 kHz 之间观察到丰富的节线结构，在 42-45 kHz 之间测量到峰值相对幅度。随着内压的增加，9 μm 和 28 μm 壁厚的圆柱的高阶模式频率增加。实验测量证实了理论模型，这些模型预测了压力相关和压力无关的谐振频率。在高压下，压力相关模式的频率计算值与测量值的误差在 2.2%以内。
