Lee Hyun-Taek, Kim Ho-Jin, Kim Chung-Soo, Gomi Kenji, Taya Minoru, Nomura Shûhei, Ahn Sung-Hoon
Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul 08826, Republic of Korea.
Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Acta Biomater. 2017 Jul 15;57:395-403. doi: 10.1016/j.actbio.2017.04.026. Epub 2017 Apr 26.
Biological materials are the result of years of evolution and possess a number of efficient features and structures. Researchers have investigated the possibility of designing biomedical structures that take advantage of these structural features. Insect shells, such as beetle shells, are among the most promising types of biological material for biomimetic development. However, due to their intricate geometries and small sizes, it is challenging to measure the mechanical properties of these microscale structures. In this study, we developed an in-situ testing platform for site-specific experiments in a focused ion beam (FIB) system. Multi-axis nano-manipulators and a micro-force sensor were utilized in the testing platform to allow better results in the sample preparation and data acquisition. The entire test protocol, consisting of locating sample, ion beam milling and micro-mechanical bending tests, can be carried out without sample transfer or reattachment. We used our newly devised test platform to evaluate the micromechanical properties and structural features of each separated layer of the beetle horn shell. The Young's modulus of both the exocuticle and endocuticle layers was measured. We carried out a bending test to characterize the layers mechanically. The exocuticle layer bent in a brick-like manner, while the endocuticle layer exhibited a crack blunting effect.
This paper proposed an in-situ manipulation/test method in focused ion beam for characterizing micromechanical properties of beetle horn shell. The challenge in precise and accurate fabrication for the samples with complex geometry was overcome by using nano-manipulators having multi-degree of freedom and a micro-gripper. With the aid of this specially designed test platform, bending tests were carried out on cantilever-shaped samples prepared by focused ion beam milling. Structural differences between exocuticle and endocuticle layers of beetle horn shell were explored and the results provided insight into the structural advantages of each biocomposite structure.
生物材料是多年进化的产物，具有许多高效的特征和结构。研究人员已经研究了设计利用这些结构特征的生物医学结构的可能性。昆虫外壳，如甲虫壳，是仿生开发中最有前途的生物材料类型之一。然而，由于其复杂的几何形状和小尺寸，测量这些微观结构的力学性能具有挑战性。在本研究中，我们开发了一个用于聚焦离子束（FIB）系统中特定位置实验的原位测试平台。测试平台中使用了多轴纳米操纵器和微力传感器，以便在样品制备和数据采集方面获得更好的结果。整个测试协议，包括定位样品、离子束铣削和微机械弯曲测试，可以在不进行样品转移或重新附着的情况下进行。我们使用新设计的测试平台评估了甲虫角壳各分离层的微观力学性能和结构特征。测量了外表皮和内表皮层的杨氏模量。我们进行了弯曲测试以从力学角度表征这些层。外表皮层以类似砖块的方式弯曲，而内表皮层表现出裂纹钝化效应。
本文提出了一种在聚焦离子束中进行原位操纵/测试的方法，用于表征甲虫角壳的微观力学性能。通过使用具有多自由度的纳米操纵器和微夹钳，克服了对具有复杂几何形状的样品进行精确制造的挑战。借助这个专门设计的测试平台，对通过聚焦离子束铣削制备的悬臂形样品进行了弯曲测试。探索了甲虫角壳外表皮和内表皮层之间的结构差异，结果为每种生物复合结构的结构优势提供了见解。
