Development of new microfluidic devices based on collective motion control of magnetic rotors

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14649
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: Osaka University
• Principal Investigator: Matsunaga Daiki 大阪大学, 大学院基礎工学研究科, 准教授 (40833794)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 磁性粒子 / ストークス流れ / 集団運動 / 微小流体デバイス / 磁性液滴

Outline of Final Research Achievements

In this research project, our aim was to explore various patterns of collective motion exhibited by a group of magnetic micro-objects, specifically magnetic droplets and magnetic swimmers, when suspended in a fluid and subjected to an external magnetic field. We analyzed these phenomena from a mechanical perspective and aimed to construct a comprehensive theoretical framework for controlling collective motion. Through this project, we successfully demonstrated that the rheological properties and collective motion of ferromagnetic droplets can be manipulated by applying an external magnetic field in the presence of shear flow. Furthermore, we observed the emergence of diverse collective motion patterns (such as axial focusing, clustering, and condensation) of magnetic swimmers under Poiseuille flow, depending on the conditions of the magnetic field. Our findings are published in five international academic journals.

Free Research Field

流体力学

Academic Significance and Societal Importance of the Research Achievements

流体中に懸濁した磁性体の集合に対して外部から一様磁場を印加したとき，磁性体の間には流体・磁気相互作用が同時に働くため，磁場の条件により立ち現れる集団運動モードの予測は自明ではない．本研究課題では磁性体一体の振る舞いを詳細に明らかにした上で多体問題へと系をスケールアップしたことにより，流体・磁気相互作用の両者の存在によってはじめて現れる新奇な集団運動を発見し報告するとともに，これら集団運動を制御する包括的な理論体系を構築することができた．得られた発見・理論は，機能性流体・材料としての磁性体の可能性を大きく拡張するものであり，医療応用研究も盛んな微小流体デバイスへの応用・新分野の創成が期待される．