The physical properties of the stick insect pad secretion are independent of body size.
The physical properties of the stick insect pad secretion are independent of body size.
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竹节虫垫分泌物的物理特性与体型无关。
DOI：
10.1098/rsif.2022.0212
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Kaimaki DM
中科院分区：
文献类型：
--
作者：
Kaimaki DM
许多昆虫利用粘附器官来攀爬。附着在表面上的能力是有利的，但随着动物的生长，由于表面积与体积比的相关减少，这种能力越来越受到挑战。先前的研究表明，一些攀爬动物通过系统地改变其粘性垫可以承受的单位面积的最大力来克服这种结垢问题。随着它们的生长，它们的粘附器官变得更加有效，这一观察结果对于仿生粘合剂的设计也具有重要意义。这种效率变化的根源是什么？在昆虫中，粘附接触是由液体薄膜介导的，被认为可以通过毛细管力和粘性力提高粘附性能。在这里，我们使用干涉反射显微镜和去湿实验来测量印度竹节虫跗骨前粘性垫分泌物的接触角和去湿速度，其质量变化超过两个数量级。接触角和去湿速度均不会随体重发生显着变化，这表明垫分泌物的关键物理特性（其表面张力和粘度）是大小不变的。因此，观察到的垫效率变化不太可能是由于垫分泌物物理特性的系统变化引起的；分泌物的功能作用仍不清楚。
Many insects use adhesive organs to climb. The ability to cling to surfaces is advantageous but is increasingly challenged as animals grow, due to the associated reduction in surface-to-volume ratio. Previous work has demonstrated that some climbing animals overcome this scaling problem by systematically altering the maximum force per area that their adhesive pads can sustain; their adhesive organs become more efficient as they grow, an observation which is also of substantial relevance for the design of bioinspired adhesives. What is the origin of this change in efficiency? In insects, adhesive contact is mediated by a thin film of a liquid, thought to increase adhesive performance via capillary and viscous forces. Here, we use interference reflection microscopy and dewetting experiments to measure the contact angle and dewetting speed of the secretion of pre-tarsal adhesive pads of Indian stick insects, varying in mass by over two orders of magnitude. Neither contact angle nor dewetting speed change significantly with body mass, suggesting that the key physical properties of the pad secretion—its surface tension and viscosity—are size-invariant. Thus, the observed change in pad efficiency is unlikely to arise from systematic changes of the physical properties of the pad secretion; the functional role of the secretion remains unclear.