Construction of the thermally driving mechanism using micro/nanoscale surface structure

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04279
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Chubu University (2022); Ube National College of Technology (2020)
• Principal Investigator: YONEMURA Shigeru 中部大学, 工学部, 教授 (00282004)
• Co-Investigator(Kenkyū-buntansha): 山口 浩樹 名古屋大学, 工学研究科, 准教授 (50432240)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 分子流体工学 / クヌッセン力 / 希薄気体力学

Outline of Final Research Achievements

By numerical experiments, we showed that in the case when a cold object is located within a distance of about mean free path of gas molecules from the ratchet surface of a hot substrate, Knudsen forces are exerted on the two bodies in such a way to slide them. Furthermore, we succeeded in predicting the force theoretically. This theory revealed the mechanism of generation of this Knudsen force. Based on the mechanism, we proposed a surface structure which induces a stronger Knudsen force and showed that we can obtain the force more than twice as strong as the force for usual ratchet. Moreover, although in the past this Knudsen force had been confirmed only in the numerical experiments, in this project we successfully confirmed this force in practical experiments and measured its strength.

Free Research Field

流体工学

Academic Significance and Societal Importance of the Research Achievements

Crookesのラジオメーターの駆動力はクヌッセン力の一種と言えるので、クヌッセン力は非常に古くから研究されてきたと言える。また、近年の微細加工技術の向上から、MEMSやNEMSなどのマイクロデバイスの発展が著しい。その構造の微細化に伴い、クヌッセン数が高くなるため、クヌッセン力が顕在化し、その利用が期待できる。しかし、クヌッセン力を駆動力に利用したデバイスはまだほとんど世に出ていない。そのような状況の中で、本研究では、クヌッセン力を用いた新たな一つの動力機構を提案した。これは、学術的にも応用面においてもインパクトが大きいことであると言える。