Department of Electronic Engineering, Kwangwoon University, Seoul 01897, Republic of Korea.
Sensors (Basel). 2022 Nov 21;22(22):9006. doi: 10.3390/s22229006.
We previously conducted an empirical study on Langevin type transducers in medical use by examining the heat effect on porcine tissue. For maximum acoustic output, the transducer was activated by a continuous sinusoidal wave. In this work, pulsed waves with various duty factors were applied to our transducer model in order to examine their effect on functionality. Acoustic power, electro-acoustic conversion efficiency, acoustic pressure, thermal effect on porcine tissue and bovine muscle, and heat generation in the transducer were investigated under various input conditions. For example, the results of applying a continuous wave of 200 V and a pulse wave of 70% duty factor with the same amplitude to the transducer were compared. It was found that continuous waves generated 9.79 W of acoustic power, 6.40% energy efficiency, and 24.84 kPa acoustic pressure. In pulsed excitation, the corresponding values were 9.04 W, 8.44%, and 24.7 kPa, respectively. The maximum temperature increases in bovine muscle are reported to be 83.0 °C and 89.5 °C for each waveform, whereas these values were 102.5 °C and 84.5 °C in fatty porcine tissue. Moreover, the heat generation around the transducer was monitored under continuous and pulsed modes and was found to be 51.3 °C and 50.4 °C. This shows that pulsed excitation gives rise to less thermal influence on the transducer. As a result, it is demonstrated that a transducer triggered by pulsed waves improves the energy efficiency and provides sufficient thermal impact on biological tissues by selecting proper electrical excitation types.
我们之前通过研究猪组织的热效应，对医用兰杰文式换能器进行了实证研究。为了获得最大的声波输出，我们使用连续正弦波来激活换能器。在这项工作中，我们将各种占空比的脉冲波应用于我们的换能器模型，以研究它们对功能的影响。在各种输入条件下，研究了声功率、电声转换效率、声压、猪组织和牛肌肉的热效应以及换能器中的热产生。例如，将 200V 的连续波和具有相同幅度的 70%占空比的脉冲波施加到换能器上的结果进行了比较。结果发现，连续波产生了 9.79W 的声功率、6.40%的能量效率和 24.84kPa 的声压。在脉冲激励下，相应的值分别为 9.04W、8.44%和 24.7kPa。报道称，每种波形在牛肌肉中的最大温升分别为 83.0°C 和 89.5°C，而在脂肪猪组织中的最大温升分别为 102.5°C 和 84.5°C。此外，在连续和脉冲模式下监测了换能器周围的发热情况，发现分别为 51.3°C 和 50.4°C。这表明脉冲激励对换能器的热影响较小。因此，结果表明，通过选择适当的电激励类型，由脉冲波触发的换能器可以提高能量效率，并对生物组织产生足够的热冲击。
