Swimming Characteristics of Bioinspired Helical Microswimmers Based on Soft Lotus-Root Fibers.

Jia Liu,Yanming Guan,Chengwei Ye,Xinyu Wu,Tiantian Xu,Xiaohui Yan

doi:10.3390/mi8120349

Abstract

Various kinds of helical swimmers inspired by E. coli bacteria have been developed continually in many types of researches, but most of them are proposed by the rigid bodies. For the targeted drug delivery, the rigid body may hurt soft tissues of the working region with organs. Due to this problem, the biomedical applications of helical swimmers may be restricted. However, the helical microswimmers with the soft and deformable body are appropriate and highly adaptive in a confined environment. Thus, this paper presents a lotus-root-based helical microswimmer, which is fabricated by the fibers of lotus-root coated with magnetic nanoparticles to active under the magnetic fields. The helical microstructures are derived from the intrinsic biological structures of the fibers of the lotus-root. This paper aims to study the swimming characteristic of lotus-root-based microswimmers with deformable helical bodies. In the initial step under the uniform magnetic actuation, the helical microswimmers are bent lightly due to the heterogeneous distribution of the internal stress, and then they undergo a swimming motion which is a spindle-like rotation locomotion. Our experiments report that the microswimmers with soft bodies can locomote faster than those with rigid bodies. Moreover, we also find that the curvature of the shape decreases as a function of actuating field frequency which is related to the deformability of lotus-root fibers.

Highlights

Artificial micro-/nanorobots have attracted lots of researchers to carry on extensive study due to their considerable promise for diverse biomedical tasks such as targeted therapy [1,2,3,4,5,6,7,8,9], tissue removal [10,11] and micro-manipulation [12,13,14,15]
Zhang et al [26] reported artificial bacterial flagella (ABF) that can swim in a controllable fashion using weak magnetic fields and analyzed the manipulated performance manipulated by the thrust force
The new helical microswimmers are fabricated by the simple coating of lotus-root-based fibers with a thin magnetic layer

Summary

Introduction

Artificial micro-/nanorobots have attracted lots of researchers to carry on extensive study due to their considerable promise for diverse biomedical tasks such as targeted therapy [1,2,3,4,5,6,7,8,9], tissue removal [10,11] and micro-manipulation [12,13,14,15]. Inspired by mastigoneme structures in nature, the research group from Swiss Federal Institute of Technology Zurich (ETH Zurich) fabricated an artificial helical microswimmers with multiple flagella and mastigonemes, modeled its propulsion model and studied the relation between the length and the velocity [19]. Nourmohammadi et al [22] proposed a 3-DOF swimming microrobot with three helical flagella and its dynamical model. Xu et al [30] carried on the extended experiment to analysis the four factors ( pitch, turn, width, thickness). In all, these researches focused on the swimming characteristics for the rigid body of the helical microswimmer

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