How efficient is towing a cargo by a micro-swimmer?

Collinear swimmer propelling a cargo sphere at low Reynolds number

The swimming velocity and rate of dissipation of a linear chain consisting of two or three little spheres and a big sphere is studied on the basis of low Reynolds number hydrodynamics. The big sphere is treated as a passive cargo, driven by the tail of little spheres via hydrodynamic and direct elastic interaction. The fundamental solution of Stokes' equations in the presence of a sphere with no-slip boundary condition, as derived by Oseen, is used to model the hydrodynamic interactions between the big sphere and the little spheres.

Collective entrainment and confinement amplify transport by schooling micro-swimmers

Micro-swimmers can serve as cargo carriers that move deep inside complex flow networks. When a school collectively entrains the surrounding fluid, their transport capacity can be enhanced. This effect is quantified with good agreement between experiments with self-propelled droplets and a confined Brinkman squirmer model. The volume of liquid entrained can be much larger than the droplet itself, amplifying the effective cargo capacity over an order of magnitude, even for dilute schools. Hence, biological and engineered swimmers can efficiently transport materials into confined environments.

3-D Printed Swimming Microtori for Cargo Transport and Flow Manipulation

Through billions of years of evolution, microorganisms mastered unique swimming behaviors to thrive in complex fluid environments. Limitations in nanofabrication have thus far hindered the ability to design and program synthetic swimmers with the same abilities. Here we encode multi-behavioral responses in artificial swimmers such as microscopic, self-propelled tori using nanoscale 3D printing. We show experimentally and theoretically that the tori continuously transition between two primary swimming modes in response to a magnetic field. The tori also manipulate and transport other artificial…

Magnetically actuated artificial microswimmers as mobile microparticle manipulators

Micro-scale swimming robots have been envisaged for many medical applications such as targeted drug delivery, where the microrobot will be expected to navigate in a fluid through channels carrying a payload. Alternatively, in many cases, such a payload does not have to be physically bound to the swimmer, but may be instead manipulated and steered through the channel by the microrobot. We investigate this problem of contactless manipulation of a microparticle by mobile microswimmer in a fluid at low Reynolds number. We consider a model of a magnetically actuated artificial microswimmer, whose l…

通过形状和货物尺寸调节微型机器人的逆流游泳

Tuning upstream swimming of micro-robots by shape and cargo size

本研究通过完全解析的流体动力学模拟，揭示了微型机器人形状和货物尺寸如何影响其逆流重新定向机制，发现拉式微型机器人在多数流动强度下最快，而推式微型机器人存在非平凡最优值，为控制微型游泳者导航及微生物趋流性研究提供了理论依据。

Optimal shapes of artificial bead-spring micro-carriers at low Reynolds numbers

Bead-based micro-swimmers are promising systems for payload delivery on the micro-scale. However, the principles underlying their optimal design are not yet fully understood. Here we study a simple device consisting of three arbitrarily-shaped beads connected by two springs. We analytically determine the most favorable kinematic parameters for sinusoidal driving, and show how the swimmer changes from being a pusher to a puller. For cargo carrying ellipsoidal beads, we perform geometric optimization under the constraint of a constant total volume or surface area, with the aim of maximizing the …