Preformation Characterization of a Torque-Driven Magnetic Microswimmer With Multi-Segment Structure

Liuxi Xing,Pan Liao,Dongfang Li,Dong Sun,Hangjie Mo

doi:10.1109/access.2021.3058527

Abstract

Magnetically powered microswimmers exhibit various advantages in practical applications, including simplified propulsion mechanism of nonreciprocal motion in a low Reynolds (Re) number environment, high flexibility, and high efficiency. Inspired by the morphological and dynamic analyses of microscale nonreciprocal locomotion, this study characterizes the properties of torque-driven segmented microswimmers that actuated by an external oscillating magnetic field. The proposed microswimmer includes a magnetized head and several non-magnetized rigid body segments fabricated by two-photon lithography. The components of the microswimmer are linked together by rigid mechanical joints with an angle limiting mechanism, thereby forming simplified and discrete wave locomotion in a low Reynolds number environment. The motion of this multi-segment structure with different segment number is analyzed, and swimming locomotion involving segment interaction of the microswimmers and ambient liquid is characterized. Theoretical and experimental studies indicate that a minimum of three segments are needed to enable the microswimmers to move forward, whereas having four segments exhibits the best comprehensive performance. Based on this analysis, the geometric parameters of the four-segment microswimmers are further optimized, and experiments verify the enhancement of its motion capacity in a low Re number regime.

Highlights

Considerable research attention recently focus on microrobots that can move in a fluidic environment, especially off-board microrobots driven by external energy sources such as light, thermal, ultrasonic, electrical, or magnetic fields [1]–[6]
A force-driven microrobot can be directly dragged by a magnetic gradient force [14], whereas a torque-driven swimming microrobot or microswimmers is driven by locomotion force produced by oscillating microrobots and squeezing ambient liquid [15]
This paper aims to fill in the gap by characterizing the driven mechanism and motion performance of the microswimmer with different segment number, based on which the ideal number of segments is recommended for the first time

Summary

Introduction

Considerable research attention recently focus on microrobots that can move in a fluidic environment, especially off-board microrobots driven by external energy sources such as light, thermal, ultrasonic, electrical, or magnetic fields [1]–[6]. Magnetdriven microrobots attract particular attention because of its high remote control performance and magnetic field that can penetrate through the body with little absorption and harm to living organisms [7]. These advantages are demonstrated in several experiments such as cell culturing [8], cell transportation [9], articular regeneration [10], and biohybrid targeted immunotherapy [11].

Objectives

Methods

Findings

Conclusion