Description
Imagine, in the future, microbots autonomously reach a target inside human body that needs to be healed. They disperse a drug around the infected area or perform surgery after which they self-disintegrate. When swimming through a fluid environment like blood plasma, these microbots are called active particles. Autonomous motion of active particles is a rapidly evolving and advancing area of science and technology. It promises to revolutionise how we treat diseases. Furthermore, the study of collective motion of active particles is a fundamentally important scientific problem, and has given rise to anew field, called active matter [1]. While nature abounds with micro-swimmers such as bacteria or sperm cells that can explore their three-dimensional environment, we do not have similar artificial active particles. Most previous work have focused on development of two-dimensional active particles. Naturally, an important question arises: how can we create, control and manipulate artificial active particles in three-dimensions?In this work, we exploit two fluid mechanical instabilities and particle chirality to create active particles in a bulk fluid. The first system consists of dielectric particles suspended in a weakly conducting fluid known to spontaneously start rotating under the action of a sufficiently strong uniform DC electric field due to the Quincke rotation instability [2, 3]. This rotation can be converted into translation when the particles are placed near a surface providing useful model systems for active matter [4, 5]. Using a combination of numerical simulations and theoretical models, we demonstrate that it is possible to convert this spontaneous Quincke rotation into spontaneous translation in a plane perpendicular to the electric field in the absence of surfaces by relying on geometrical asymmetry instead [6]. The second system consists of ferromagnetic particles subject to an AC magnetic field.In the absence of particle inertia, the dipole moment of the particle rotates with the magnetic field and the colloid moves back and forth with no net motion when placed near a surface. However, a small amount of inertia breaks the symmetry of the clock-wise/counter-clockwise rotation and the particle propels itself in a particular direction.A collection of such self-propelled particles have been shown to display collective motion[7]. Using numerical simulations based on slender body theory, we demonstrate that it is possible to create active chiral ferromagnetic particles in a bulk fluid that do not require a surface for propulsion.| Period | 25 May 2021 |
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| Event title | 7th International Conference on Micro and Nano Flows, Imperial College London |
| Event type | Conference |
| Location | London, United KingdomShow on map |
| Degree of Recognition | International |