Untethered gripper-type hydrogel millirobot actuated by electric field and magnetic field

Abstract

This paper proposes a novel concept of an untethered gripper-type hydrogel millirobot that can be actuated by electric and magnetic fields. The proposed millirobot has two arms consisting of anodic and cathodic electroactive hydrogels, which generate bending motions by the electric field to enable the 'open' and 'close' motion of a gripper. Meanwhile, it can locomote using the magnetic field due to the magnetic nanoparticles (MNPs) contained inside its two arms. Therefore, when the electric and magnetic fields are used in combination, the proposed millirobot can simultaneously perform gripping motion and locomotion. In this study, we first investigated the bending motion characteristics of each electroactive hydrogel when an electric field was applied to both the anodic and the cathodic electroactive hydrogels of the proposed millirobot. Then, by applying an electric field to the untethered gripper-type hydrogel millirobot which combines the two hydrogels in a gripper form, we confirmed that each hydrogel moves in the opposite direction at the same electric field, while the millirobot implements the open and close gripping motions. Moreover, the proposed robot can locomote in the desired direction by applying a magnetic field through an electromagnetic actuation (EMA) system. Finally, it was verified that this robot can demonstrate gripping motion and locomotion simultaneously by the electric and magnetic field integrated system.

A Review of Recent Advances in Electrically Driven Polymer‐Based Flexible Actuators: Smart Materials, Structures, and Their Applications

“…[ 76 ] In recent days, EAHs were also utilized as a millirobot gripper whose movement was controlled by both electric and magnetic fields. [ 154 ]…”

“…[76] In recent days, EAHs were also utilized as a millirobot gripper whose movement was controlled by both electric and magnetic fields. [154] As discussed earlier, although bilayer ETA-based manipulators have the disadvantage of low gripping force owing to their driving principle, they can be designed with diverse shapes such as hand-shape, T-shape, and X-shape. [136] For example, Li et al prepared an highly oriented CNT paper, so they could fabricate multiform actuations with diverse electrode designs.…”

Stimuli‐responsive hydrogels: Fabrication and biomedical applications

“…Unlike light or other non-contact stimuli, the magnetic and electric field show unique advantages in applications requiring non-invasive fine operation in narrow and small areas. [147][148][149][150] Thus, magnetic/electric responsive hydrogels, which can perform translation between structural defor-mation/mechanical displacement and magnetic/electric signal, attract general attention in field of biomimetic and soft robotic material, [151][152][153][154][155][156][157] drug delivery, [158][159][160][161] and biotechnology and biomedical engineering. [162][163][164][165][166] Recently, Du's group 167 reported a millirobot with neodymium-ironboron microparticles in the head.…”

Recent progress in magnetic applications for micro- and nanorobots

“…Therefore, the combination of magnetism and electricity has been widely used in the design of various magnetic MNRs. Kim et al [64] proposed a hydrogel microrobot based on the combination of an electroactive hydrogel and MNPs. Electroactive hydrogels are usually made of a single hydrogel [65].…”