Active Reversible Swimming of Magnetically Assembled "Microscallops" in Non-Newtonian Fluids.
Active Reversible Swimming of Magnetically Assembled "Microscallops" in Non-Newtonian Fluids.
复制标题
非牛顿流体中磁组装“微扇贝”的主动可逆游动。
DOI：
10.1021/acs.langmuir.9b03698
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
O. Velev
中科院分区：
文献类型：
--
作者：
Koohee Han;C. W. Shields;B. Bharti;P. Arratia;O. Velev
能够在低雷诺数下主动游动的小型化装置具有根本的重要性，并且具有潜在的生物医学用途。胶体微泳体的设计不仅需要实现可重构结构，还需要了解它们在低雷诺数下与介质的相互作用。我们研究了由非对称磁性立方体组成的“微扇贝”的动力学，这些立方体是用磁场组装和驱动的。实现定向推进的一种方法是通过将这种微泳者的往复运动与非牛顿流体固有的非线性流变学耦合来打破粘性力的对称性。当放置在剪切稀化流体中时，由微扇贝的时间不对称冲程施加的非均匀剪切应力产生的局部粘度梯度通过我们称之为“自粘泳”的效应产生推进推力。令人惊讶的是，我们发现推进的方向随着这些组件的大小和结构而变化。我们分析了他们的方向性推进的起源和解释的变量推进方向的多个平衡域的剪切耗散周围的微尺度结构。这些微泳者的运动原理可以扩展到其他由胶体尺度单元组装而成的可重构微型机器人。
Miniaturized devices capable of active swimming at low Reynolds numbers are of fundamental importance and possess potential biomedical utility. The design of colloidal microswimmers requires not only miniaturizing reconfigurable structures, but also understanding their interactions with media at low Reynolds numbers. We investigate the dynamics of "microscallops" made of asymmetric magnetic cubes, which are assembled and actuated using magnetic fields. One approach to achieve directional propulsion is to break the symmetry of the viscous forces by coupling the reciprocal motions of such microswimmers with the nonlinear rheology inherent to non-Newtonian fluids. When placed in shear-thinning fluids, the local viscosity gradient resulting from non-uniform shear stresses exerted by time-asymmetric strokes of the microscallops generates propulsive thrust through an effect we term "self-viscophoresis". Surprisingly, we found that the direction of propulsion changes with the size and structure of these assemblies. We analyze the origins of their directional propulsion and explain the variable propulsion direction in terms of multiple counterbalancing domains of shear dissipation around the microscale structures. The principles governing the locomotion of these microswimmers may be extended to other reconfigurable microbots assembled from colloidal scale units.
影响因子：
19.6
作者：
Aubret, Antoine;Youssef, Mena;Palacci, Jeremie
通讯作者：
Palacci, Jeremie
影响因子：
16.6
作者：
Qiu, Tian;Lee, Tung-Chun;Mark, Andrew G.;Morozov, Konstantin I.;Muenster, Raphael;Mierka, Otto;Turek, Stefan;Leshansky, Alexander M.;Fischer, Peer
通讯作者：
Fischer, Peer