The interaction of polymer dispersed liquid crystal sensors with ultrasound
The interaction of polymer dispersed liquid crystal sensors with ultrasound
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DOI：
10.1063/1.5139598
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发表时间：
2020-01-27
影响因子：
4
通讯作者：
Trushkevych, O.
中科院分区：
文献类型：
--
作者：
Edwards, R. S.;Ward, J.;Trushkevych, O.
聚合物分散液晶（PDLC）已被证明通过声光效应对超声波敏感。在较宽的频率范围（0.3-10 MHz）内研究了 PDLC 的声光响应。我们证明，产生 PDLC 薄膜声光透明所需的位移可以低至几纳米，这至少比 PDLC 液滴尺寸小 10(3) 倍，比 PDLC 层厚度小 10(5) 倍，并且与液晶成分的分子尺寸相当。这表明 PDLC 中的声光效应是由于扭矩或流量下液晶重新取向的微观效应而不是宏观液滴变形引起的液晶重新取向。清理所需的位移通过指数衰减与操作频率相关。我们将观察到的频率响应归因于围绕液晶短轴的旋转运动的冻结。报告的频率依赖性和所需的位移表明此处描述的效果和材料可用于无损测试环境中的超声可视化。
Polymer dispersed liquid crystals (PDLCs) have been shown to be sensitive to ultrasound through the acousto-optic effect. The acousto-optic response of PDLCs was studied over a broad frequency range (0.3-10 MHz). We demonstrate that the displacements required to produce acousto-optic clearing of PDLC films can be as low as a few nanometers, which is at least 10(3) times smaller than the PDLC droplet size, is 10(5) times smaller than the PDLC layer thickness, and of the order of the molecular size of the liquid crystal constituents. This suggests that the acousto-optic effect in PDLCs is due to the microscopic effects of the LC reorientation under torques or flows rather than the LC reorientation through macroscopic droplet deformation. The displacement required for clearing is related to the frequency of operation via an exponential decay. We attribute the observed frequency response to a freezing out of the rotational motion around the short axis of the liquid crystal. The reported frequency dependence and displacements required indicate that the effects and materials described here could be used for ultrasound visualization in a non-destructive testing context.