Numerical modelling of chirality-induced bi-directional swimming of artificial flagella

Abstract

Biomimetic micro-swimmers can be used for various medical applications, such as targeted drug delivery and micro-object (e.g. biological cells) manipulation, in lab-on-a-chip devices. Bacteria swim using a bundle of flagella (flexible hair-like structures) that form a rotating cork-screw of chiral shape. To mimic bacterial swimming, we employ a computational approach to design a bacterial (chirality-induced) swimmer whose chiral shape and rotational velocity can be controlled by an external magnetic field. In our model, we numerically solve the coupled governing equations that describe the system dynamics (i.e. solid mechanics, fluid dynamics and magnetostatics). We explore the swimming response as a function of the characteristic dimensionless parameters and put special emphasis on controlling the swimming direction. Our results provide fundamental physical insight on the chirality-induced propulsion, and it provides guidelines for the design of magnetic bi-directional micro-swimmers.

Soft-bodied adaptive multimodal locomotion strategies in fluid-filled confined spaces

“…To model the robot locomotion and fluid flow created by the robot, we used a computational fluid dynamics (CFD) model ( 59 , 60 ), which could accurately describe the robot motion and the deformation-induced fluid flow at low Re . In the CFD model, the midplane of the robot was meshed by shell elements.…”

Coordination of two opposite flagella allows high-speed swimming and active turning of individual zoospores

“…Movie 3 for a long run of a zoospore swimming in water). It has been shown that microswimmers with chiral shape of the body and asymmetric arrangement of their flagella are among the reasons causing this self rotational motion [26, 36, 37]. By quantifying the pitch of the helical trajectories, we achieve the rotational speed of the cell body approximately 3.5 π rad s −1 .…”

Resistive force theory-based analysis of magnetically driven slender flexible micro-swimmers

“…For example, a fully coupled implicit solver for the interaction of slender flexible shells and Stokes flow is presented in [17] where geometrically nonlinear elastic structural response is resolved by FEM, and BEM is used for the Stokes flow. The resulting framework has been successfully used to analyze artificial cilia and to investigate swimming direction control strategies, see [18]. However, a simpler, solely finite element-based approach would be a valuable tool to address similar problems within shorter computational times.…”

“…However, to the author's knowledge, the treatment of thin shell-type flexible bodies in combination with the resistive force theory has not been addressed fully yet. The only work in this context was presented in the appendix of reference [18] in which an RFT-based analysis of a slender flexible shell was carried out. However, in this analysis, the elastic forces developing in the slender deformable body were not taken into account, and in that sense it was incomplete.…”