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Micromachines swimming in viscoelastic fluids
http://hdl.handle.net/10748/00011528
http://hdl.handle.net/10748/00011528f6618d3a-fd82-405d-869d-fe859b89dd02
| 名前 / ファイル | ライセンス | アクション |
|---|---|---|
T01584-001.pdf (1.6 MB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||||
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| 公開日 | 2020-03-06 | |||||||
| タイトル | ||||||||
| タイトル | Micromachines swimming in viscoelastic fluids | |||||||
| 言語 | ||||||||
| 言語 | eng | |||||||
| 資源タイプ | ||||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_46ec | |||||||
| 資源タイプ | thesis | |||||||
| 著者 |
Yasuda, Kento
× Yasuda, Kento
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| 著者(ヨミ) |
ヤスダ, ケント
× ヤスダ, ケント |
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| 著者別名 |
安田, 健人
× 安田, 健人 |
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| 抄録 | ||||||||
| 内容記述タイプ | Abstract | |||||||
| 内容記述 | Microswimmers are tiny machines that swim in a fluid, such as sperm cells or motile bacteria, and they are expected to be applied to microfluidics and microsystems. By transforming chemical energy into mechanical work, microswimmers change their shape and move in viscous environments. Over the length scale of microswimmers, the fluid forces acting on them are governed by the effect of viscous dissipation. According to Purcell's scallop theorem, time-reversal body motion cannot be used for locomotion in a Newtonian fluid. As one of the simplest models exhibiting broken time-reversal symmetry, Najafi and Golestanian proposed a three-sphere swimmer, in which three in-line spheres are linked by two arms of varying length. First, we discuss the locomotion of a three-sphere microswimmer in a viscoelastic medium and propose a new type of active microrheology. We derive a relation that connects the average swimming velocity and the frequency-dependent viscosity of the surrounding medium. In this relation, the viscous contribution can exist only when the time-reversal symmetry is broken, whereas the elastic contribution is present only when the structural symmetry of the swimmer is broken. Purcell's scallop theorem breaks down for a three-sphere swimmer in a viscoelastic medium. Next, we discuss the dynamics of a generalized three-sphere microswimmer in which the spheres are connected by two elastic springs. The natural length of each spring is assumed to undergo a prescribed cyclic change. We analytically obtain the average swimming velocity as a function of the frequency of cyclic change in the natural length. In the low-frequency region, the swimming velocity increases with frequency, and its expression reduces to that of the original three-sphere model by Najafi and Golestanian. Conversely, in the high-frequency region, the average velocity decreases with increasing frequency. Such behavior originates from the intrinsic spring relaxation dynamics of an elastic swimmer moving in a viscous fluid. Finally, we discuss the directional motion of an elastic three-sphere micromachine in which the spheres are in equilibrium with independent heat baths having different temperatures. Even in the absence of prescribed motion of the springs, such a micromachine can gain a net motion due purely to thermal fluctuations. A relation connecting the average velocity and the temperatures of the spheres is analytically obtained. This velocity can also be expressed in terms of average heat flows in the steady state. Our model suggests a new mechanism for locomotion of micromachines in nonequilibrium biological systems. | |||||||
| 内容記述 | ||||||||
| 内容記述タイプ | Other | |||||||
| 内容記述 | 首都大学東京, 2018-03-25, 修士（理学） | |||||||
| 書誌情報 | p. 1-148, 発行日 2018-03-25 | |||||||
| 著者版フラグ | ||||||||
| 出版タイプ | AM | |||||||
| 出版タイプResource | http://purl.org/coar/version/c_ab4af688f83e57aa | |||||||
| その他のタイトル | ||||||||
| その他のタイトル | 粘弾性体中を遊泳するマイクロマシン | |||||||
| 学位名 | ||||||||
| 学位名 | 修士（理学） | |||||||
| 学位授与機関 | ||||||||
| 学位授与機関名 | 首都大学東京 | |||||||
| 学位授与年月日 | ||||||||
| 学位授与年月日 | 2018-03-25 | |||||||
