Biomechanical Investigation of Insect Leg Joints

昆虫的腿关节在它们的一生中经历了数百万次的台阶、跳跃和弯曲运动；并超越了大多数人造机械装置的耐用性和摩擦效率。相对于身体长度，昆虫超过了许多动物跳跃的高度，并以更快的速度加速它们的身体。此外，昆虫关节的用力是其体重的数十至数百倍，如蛙鼠（414倍）、跳蚤（135倍）、蝗虫（8倍），远远超过人类（2-3倍）。然而，虽然很早以前人们就认识到昆虫关节的有效功能，但昆虫关节有效运作的机制仍然是未知的。本研究旨在填补这一知识空白，并有两个组成部分，以整合研究和教育。第一部分致力于增加代表性不足的群体对学术研究的参与，第二部分涉及课程开发。因此，任何机器要运转和移动，都必须提供能量来克服摩擦。对社会和工业来说，最大限度地减少摩擦损失的能量是一个重要问题。该项目的成果将对通过生物灵感开发创新、节能和耐用的涂料具有重要价值。该项目还将包括向社区提供教育外展计划，并将学生融入研究团队。这项工作的首要目标是对控制昆虫关节的运作和效率的原则有一个基本的理解。具体来说，本研究将试图确定昆虫关节表面形态的主要特征是什么，以及这些特征如何影响昆虫关节之间的粘附；并讨论了其内部纳米结构对其弹性模量和硬度等力学性能的影响。此外，将开发与摩擦和磨损有关的结构，附着力和机械性能的模型。这些任务将使用先进的表面表征技术来完成，包括原子力显微镜、纳米压痕和纳米摩擦学。由于生物材料的结构-性能关系是生物力学和材料科学领域的当代关键问题之一，这项活动有可能通过确定昆虫腿关节的结构和形态特性来推进这一主题的当前艺术状态，这些特性以前从未被研究过。此外，对层次化纳米结构和昆虫腿关节的摩擦学特性了解甚少。因此，该项目的研究成果必将对摩擦学和生物摩擦学领域产生有益的影响。

Insect leg joints endure millions of steps, jumps, and bending motions in their lifespan; and surpass the durability and frictional efficiency of most human-made mechanical devices. Relative to body length, insects exceed the height jumped by many animals and accelerate their bodies at a much faster rate. Furthermore, the exertion force of an insect joint is tens to several hundred times their body weight as exhibited by froghoppers (414 times), fleas (135 times), and locusts (8 times), vastly exceeding that of humans (2-3 times). However, although efficient functioning of insect joints has been recognized for a long time, the mechanism by which insect joints operate efficiently is still unknown. This research aims to fill this knowledge gap, and has two components for integrating research and education. The first component strives to increase the participation of underrepresented groups in academic research and the second concerns curriculum development. Considering that, for any machine to operate and move, energy must be provided to overcome friction. Minimizing the amount of energy lost to friction is a significant issue for society and industry. The outcomes of this project will be valuable to the development of innovative, energy-efficient, and durable coatings through bio-inspiration. The project will also involve an educational outreach program to the community and the integration of students into the research team.The overarching objective of this work is to generate a fundamental understanding of the principles that govern the operation and efficiency of insect joints. Specifically, this research will seek to determine what the main features of surface morphology of insect joints are and how these features influence the adhesion between insect joints; and also the role of their internal nanostructure on their mechanical properties such as modulus of elasticity and hardness. Furthermore, models relating the structural, adhesion, and mechanical properties with friction and wear will be developed. These tasks will be achieved using advance surface characterization techniques including atomic force microscopy, nanoindentation, and nanotribometry. Since structure-property relationship of biomaterials is one of the key contemporary issues in the fields of biomechanics and materials science, this activity has potential to advance the current state of art in this topic by determining structural and morphological properties of insect leg joints that have never been studied before. Furthermore, little is known about tribological properties of hierarchical nanostructures and insect leg joints. Hence, the outcomes of this project are bound to beneficial to the field of tribology and biotribology.