University of Antwerp, Antwerp 2020, Belgium; Laboratory of Biomedical Physics (BIMEF), University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium.
Laboratory of Biomedical Physics (BIMEF), University of Antwerp, Groenenborgerlaan 171, Antwerp 2020, Belgium.
Hear Res. 2023 Sep 15;437:108840. doi: 10.1016/j.heares.2023.108840. Epub 2023 Jul 6.
While the presence of residual stress (also called prestress) in the tympanic membrane (TM) was hypothesized more than 150 years ago by von Helmholtz (1869), little experimental data exists to date. In this paper, a novel approach to study residual stress is presented. Using a pulsed laser, the New Zealand white rabbit TM is perforated at seven predefined locations. The subsequent retraction of the membrane around the holes is computed using digital image correlation (DIC). The amount of retraction is the so-called prestrain, which is caused by the release of prestress due to the perforation. By measuring the prestrain using DIC, we show that residual stress is clearly present over the entire rabbit TM surface. In total, fourteen TMs have been measured in this work. An automated approach allows tracking the holes' deformation during the measurement process and enables a more robust analysis than was previously possible. We find similar strains (around 5%) as reported in previous work, in which slits were created manually using flattened surgical needles. However, the new approach greatly reduces measurement time, which minimizes dehydration artifacts. To investigate the effect of perforation location on the TM, the spatial decrease of the prestrain (α) around the perforation was quantified. Perforations inferior to the umbo showed the least negative α values, i.e., the most gradual decrease around the hole, and were the most consistent. Perforations on other locations showed more negative α values, i.e., steeper decrease in strain, but were less consistent across samples. We also investigated the effect of the holes' creation sequence but did not observe a significant change in the results. Overall, the presented method allows for consistent residual stress measurements over the TM surface. The findings contribute to our fundamental knowledge of the mechanics of the rabbit TM and provide a basis for future work on human TMs.
虽然 von Helmholtz（1869 年）早在 150 多年前就假设了鼓膜（TM）中存在残余应力（也称为预应力），但迄今为止，很少有实验数据存在。在本文中，提出了一种研究残余应力的新方法。使用脉冲激光，在七个预定位置在新西兰白兔 TM 上穿孔。然后使用数字图像相关（DIC）计算围绕孔的膜的回缩。回缩量就是所谓的预应力，这是由于穿孔导致预应力释放而产生的。通过使用 DIC 测量预应力，我们表明残余应力明显存在于整个兔 TM 表面。在这项工作中，总共测量了十四只 TM。自动化方法允许在测量过程中跟踪孔的变形，并能够进行比以前更稳健的分析。我们发现与以前使用扁平手术针手动创建狭缝的工作中报告的相似应变（约 5%）。然而，新方法大大减少了测量时间，从而最大程度地减少了脱水伪影。为了研究穿孔位置对 TM 的影响，量化了穿孔周围预应力（α）的空间减小。位于 umbo 下方的穿孔显示出最小的负α值，即孔周围最平缓的应变下降，且最一致。其他位置的穿孔显示出更大的负α值，即应变的急剧下降，但在样本之间的一致性较差。我们还研究了孔的创建顺序的影响，但没有观察到结果有明显变化。总体而言，所提出的方法允许在 TM 表面上进行一致的残余应力测量。这些发现有助于我们对兔 TM 力学的基本认识，并为未来对人类 TM 的研究提供了基础。
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