CAREER: Biomechanics of Amphibious Fish Fins and Mechanical Principles of Stiff Lightweight Structures

这项学院早期职业发展(Career)补助金将使用工程学来发现生物力学的专门化，使两栖鱼类能够在陆地上移动。这是很有科学价值的，因为这些鱼用它们又薄又轻的鳍来施加非常大的力量在陆地上移动。通过生物实验、工程设备设计和数学建模，该项目试图揭示用于在陆地上移动的鳍的形式和功能之间的关系。在这个项目中获得的知识将对几个领域产生影响。了解行走鱼的机制将有助于解决设计能够穿越不同环境的敏捷机器人的重大挑战。这对于未来将这种机器人用于搜救行动和远程生态研究非常重要，以便前往人类不可能或不安全的地方。对于了解陆生脊椎动物是如何从大约4亿年前使用鳍在陆地上活动的水生祖先进化而来的，了解两栖鱼类也是至关重要的。该项目的协同教育和外联活动包括课程开发、针对高中生的多年支架式导师计划，以及学生开发的两栖鱼类博物馆展品，这些展品也将作为学校教师的新型教学工具。这项跨学科的研究目标是发现两栖鱼如何通过鳍设计和生物力学来承受陆地上移动的力量，并验证它们利用曲率诱导的刚度的非线性效应来抵抗地面力的假设。曲率诱导的僵硬原理有助于人类的脚抵御地面力量，而水生鱼鳍也体现了实现这一效果所需的元素。但鳍和脚的解剖表现截然不同，这就提出了两栖鱼在陆地上如何使鳍变硬的问题。该项目将采用实验和理论相结合的方法，从整个生物体(约10-100毫米)到鳍的内部结构(约10-100微米)，研究两栖鱼类(弹涂鱼和双鱼)和水生鱼类(虾虎鱼和鲱鱼)鳍的多尺度、等级和复合结构。对运动生物力学和鱼鳍结构力学具有基本影响的具体目标是：(I)使用新型光学力传感器测量在体鳍上的力，(Ii)通过两栖和水生鱼鳍的体外力学测试来确定影响鳍硬度的关键解剖要素，以及(Iii)通过结合三维微计算机断层扫描(MicroCT)、活体力和体外刚度数据与多尺度、复合弹性鳍模型，发现两栖鱼鳍的专门化，并推导出鳍形态功能空间的普遍生物力学原理。关于鳍的形状和功能关系的发现可能对生物学家研究鳍和肢体的发展和进化至关重要。此外，新颖的附属物设计可以显著提高多地形机器人的效率。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development (CAREER) grant will use engineering to discover the biomechanical specializations that allow amphibious fish to move on land. This is of scientific interest because these fish use their thin and lightweight fins to apply very large forces to move on land. Through biological experiments, engineering device design, and mathematical modeling, the project seeks to uncover relationships between the form and function of fins used to move on land. The knowledge gained in this project will impact several fields. Understanding the mechanics of walking fish will help address the substantial challenges in designing agile robots capable of traversing diverse environments. This is important for future use of such robots for search and rescue operations and remote ecological studies to go where it is impossible or unsafe for humans to go. Learning about amphibious fish is also critical for understanding how terrestrial vertebrates evolved from an aquatic ancestor that used its fins to move on land around 400 million years ago. The project’s synergistic education and outreach activities include curriculum development, a multi-year scaffolded mentorship plan for high school students, and student-developed hands-on museum exhibits on amphibious fish that will also serve as novel teaching aids for school teachers. These will be designed to broaden participation in STEM from K-12 through college and incubate the next generation of interdisciplinary scientists.This interdisciplinary research objective is to discover how the mudskipper, an amphibious fish, has specialized its fin design and biomechanics to withstand forces for moving on land and test the hypothesis that they resist ground forces using the nonlinear effect of curvature-induced stiffness. The curvature-induced stiffness principle helps human feet withstand ground forces, and aquatic fish fins also manifest elements needed for that effect. But the anatomical manifestations are quite different in fins and feet, raising the question of how amphibious fish stiffen their fins on land. The project will combine experiments with theory to investigate the multi-scale, hierarchical, and composite structure of the fins of amphibious (mudskippers and bichirs) and aquatic fish (gobies and mackerels) from the whole organism (~10–100 millimeters) down to the fin’s internal structure (~10–100 micrometers). The specific aims, with fundamental impact on locomotion biomechanics and fish fin structural mechanics, are to (i) measure in vivo forces on mudskipper fins using a novel optical force sensor, (ii) identify critical stiffness-contributing anatomical elements using in vitro mechanical tests on amphibious and aquatic fish fins, and (iii) discover the specializations of amphibious fish fins and derive generalizable biomechanical principles of a fin morpho-functional space by combining 3D micro-computed tomography (microCT), in vivo force, and in vitro stiffness data with multi-scale, composite-elastic fin models. Discoveries on the fin’s form-function relationships could be crucial for biologists studying the development and evolution of fins and limbs. Also, novel appendage designs may considerably enhance the effectiveness of multi-terrain robots.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.