Adhesive mechanisms and dynamic performance in smooth adhesive pads of insects

许多昆虫能够在光滑的表面上倒立运行，承载负载并承受相当于自身体重100倍以上的拉力。这种令人印象深刻的性能是如何实现的机制，以及它们如何掌握运行和稳定粘合接触的冲突任务，在很大程度上仍然是未知的。我们将研究蚂蚁和竹节虫的表面附着和运动，它们的腿尖上有光滑的粘性垫。将进行实验以澄清附着力是由于“湿”还是“干”粘附，即它们主要是基于垫和表面之间的流体膜的性质还是基于粘附垫表皮和基底之间的直接接触。我们将研究是否液体分泌增强粘附，如果是，在什么条件下。测量单腿的附着力（附着力和摩擦力），同时拍摄其与表面的接触区域。垫角质层和分泌物的物理特性将与现代显微镜技术进行分析，并用于比较垫性能与理论预测。为了阐明粘附机制和力随身体尺寸的缩放，我们将研究粘合垫如何从表面分离。通常，当通过剥离来分离焊盘时，力减小。我们将研究昆虫是否能够避免脱皮，如果是，它们是如何做到这一点的。为了了解昆虫如何设法将联合收割机表面附着与运动结合起来，我们将研究附着和分离过程中腿和吸盘的运动。通过分析昆虫奔跑的高速记录，我们将探索表面附着如何影响奔跑，以及昆虫如何调整它们的腿和脚来科普不同的附着条件。我们的项目将阐明昆虫如何粘附在表面上，以及它们如何控制附着力。尽管存在许多潜在的应用，但尚未开发出可控的技术粘合剂。了解昆虫如何优雅地控制附着的机制可能会导致发现用于设计新型“仿生”粘合剂的一般原理。

Many insects are capable of running upside down on a smooth surface, carrying loads and withstanding pull-off forces equivalent to more than 100 times their own body weight. The mechanisms of how this impressive performance is achieved and of how they master the conflicting tasks of running and of making stable adhesive contacts, are still largely unknown. We will investigate surface attachment and locomotion in ants and stick insects, which possess smooth adhesive pads at the tips of their legs. Experiments will be conducted to clarify whether attachment forces are due to 'wet' or dry' adhesion, i.e. whether they are mainly based on the properties of a fluid film between pad and surface or on the direct contact between the adhesive pad cuticle and the substrate. We will investigate whether the fluid secretion enhances adhesion and if so, and under what conditions. Attachment forces of single legs (adhesion and friction) will be measured while simultaneously filming their area of contact with the surface. The physical properties of pad cuticle and secretion will be analysed with modern microscopy techniques, and used to compare pad performance with theoretical predictions. To clarify the mechanism of adhesion and the scaling of forces with body size, we will study how adhesive pads detach from the surface. In general, forces are reduced when pads are detached by peeling. We will investigate whether insects are able to avoid peeling and if so, how they do this. To understand how insects manage to combine surface attachment with locomotion, we will study the movements of legs and adhesive pads during attachment and detachment. By analysing high-speed recordings of running insects, we will explore how running is influenced by surface attachment and how insects adjust their legs and feet to cope with different attachment conditions. Our project will clarify how insects adhere to surfaces and how they manage to control attachment forces. Even though numerous potential applications exist, no controllable technical adhesives have yet been developed. Understanding the mechanisms of how insects elegantly control attachment is likely to lead to the discovery of general principles useful for the design of novel 'biomimetic' adhesives.