Enhanced Precession of a Magnetic Helical Microbot in a Viscoelastic Gel
Meng Zhang, Liyuan Tan, Jyothi Kumari Mariyanna, Moonkwang Jeong, Jiyuan Tian, Ann-Sophia Müller, Tian Qiu
Abstract
Magnetic helical micro-robots (microbots) have attracted strong interest due to their unique propulsion mechanisms and potential applications in biomedical fields, particularly in minimally-invasive surgical procedures. Earlier research primarily focused on studying helical microbots in viscous liquids, while their dynamic behavior in viscoelastic solids remains largely unexplored. Here, we present an experimental study of a helical microbot operating in a viscoelastic gelatin hydrogel. The robot is fabricated by two-photon polymerization and actuated by an external rotating magnetic field. We observe that in viscoelastic solids, the robot ruptures the gel and creates a three-dimensional (3D) helical trajectory, despite the rotational axis of the driving magnetic field being fixed. Largely distinct from the propulsion behavior in a Newtonian fluid, the precession angle of the helix is significantly enhanced in the viscoelastic gel and increases with a rising rotational frequency. A dynamic model is developed using the multipole expansion method, incorporating the gel’s complex viscosity and shear-thinning properties to capture the key characteristics of this dynamic response. These findings offer new insights into the behavior of helical microbots in viscoelastic media, expanding possible application scenarios of microbots in biomedicine.
BibTeX
@inproceedings{iros2025_enhancedprecessi,
title = {Enhanced Precession of a Magnetic Helical Microbot in a Viscoelastic Gel},
author = {Meng Zhang and Liyuan Tan and Jyothi Kumari Mariyanna and Moonkwang Jeong and Jiyuan Tian and Ann-Sophia Müller and Tian Qiu},
booktitle = {IROS 2025},
year = {2025}
}