News Source: School of Mechanical Engineering

Editor: News Agency of BIT

Translator: News Agency of BIT, Zhang Zijun

Beijing Institute of Technology, July 21st, 2021: Recently, the research result, "Hairy-Layer Friction Reduction Mechanism in the Honeybee Abdomen" (by Wang Mingyue, Chen Weihua, Zhao Jieliang, Yu Li, Yan Shaoze), which was achieved jointly by Assistant Professor Zhao Jieliang’s team from School of Mechanical Engineering, Beijing institute of technology(BIT) and Professor Yan Shaoze’s team from Tsinghua University, has been published in the form of the Direct Submission, Research Article in the international journal ACS Applied Materials and Interfaces online. BIT is the first correspondent and the first author, Wang Mingyue, is a master's student jointly supervised by Associate Professor Zhao Jieliang of BIT and Professor Yan Shaoze of Tsinghua University. Zhao Jieliang and Yan Shaoze are co-corresponding authors of the paper.

We often say "Work like a honeybee, live like a butterfly", and it is easy to understand the origin of this phrase when you see honeybees busily working in the flowers. As a social insect living in clusters, honeybees don’t have the advanced verbal communication skills like humans, but they have the ability to perform a wide variety of body movements and have relatively complete verbal communication skills owing to their delicate body structure. among which the reciprocating bending and stretching of the abdomen play an irreplaceable role. This paper shows for the first time that the tiny hairs of the honeybee are able to reduce friction between the relative movements of the abdominal segmented structures, saving energy for the honeybees' daily hard-working activities and reducing wear or abrasion on the abdominal structures.

The abdomen of the honeybee is made up of several sets of hard dorsal and ventral plates overlapped in sections, which move relatively to each other tens of millions of times throughout the honeybee's life cycle. As the abdomen flexes and extends, the adjacent dorsal plates (ventral plates) slide against each other, which should inevitably generate friction. However, the team was puzzled by the actual observation that there was little wear on the overlapped ventral segment structures. The team therefore investigated the friction reduction mechanism in the abdomen of honeybees. They observed the abdominal structure and surface morphology of the honeybees under a scanning electron microscope and found dense branching villi on the exterior surface of the abdominal segments. Using atomic force microscopy, they measured the friction generated by the exoskeleton as it moved over hairy or hairless surfaces. At the same load, friction on hairy surfaces was less than that on smooth surfaces. As the load increased, the friction on the hairless surface increased, while the friction on the hairy surface did not increase significantly. The researchers calculated that the hairy surfaces reduced wear by about 60% during abdominal contractions, which saved energy for each abdominal bending and stretching movement. The researchers claimed that this accumulated energy was vital for the honeybees to carry out their daily activities, and this research could be used in the design of bionic surfaces for friction reduction in construction machinery, extending the life of engineering equipment.

Fig 1. Resistance reduction mechanism on the hairy surface of the honeybee abdomen

The results in the paper were developed with the support of two National Natural Science Foundation of China (programs of 51805293 and 52075038), one Beijing Natural Science Foundation (program of 3184050) and one BIT Academic Initiation Programme project for Young Faculty. The research was greatly assisted by Professor Wang Wenzhong, master students’ Liang Lulu, Niu Qun, Xing Jin, Wu Xiangbing from School of Mechanical Engineering, BIT, in the writing of paper and the research of experiment. School of Mechanical Engineering, BIT, State Key Laboratory of Tribology Tsinghua University and School of Life Sciences, Tsinghua University provided equipment and technical support for this research.

ACS Applied Materials & Interfaces is a young journal founded in 2009 by the American Chemical Society and has a high international reputation for publishing research on new materials and interfacial processes. Articles published in ACS AMI often represent cutting-edge and internationally leading research, scholarly reviews, significant discoveries, and subject reviews in materials science and surface interface engineering.

With team descriptions:

Zhao Jieliang, Assistant Professor and doctoral supervisor of School of Mechanical Engineering, BIT. He is mainly engaged in research on animal behaviour and mechanisms, intelligent biomechanics and bionic machinery.

Yan Shaozhe, Professor and doctoral supervisor in the Department of Mechanical Engineering, Tsinghua University. He is also a member of the Steering Sub-Committee for Teaching Basic Mechanical Courses in Higher Education, Ministry of Education. He has long been engaged in research in the fields of mechanical system dynamics, aerospace dynamics and reliability insect bionics.

The information of the paper (* are corresponding authors)

Mingyue Wang, Weihua Chen, Jieliang Zhao*, Li Yu, Shaoze Yan*. Hairy-Layer Friction Reduction Mechanism in the Honeybee Abdomen. ACS Appl. Mater. Interfaces 2021, 13, 21, 24524–24531

Link to the paper: https://pubs.acs.org/doi/10.1021/acsami.1c05500