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Spinning-enabled Wireless Amphibious Origami Millirobot
Qiji Ze, Shuai Wu, Jize Dai, Sophie Leanza, Gentaro Ikeda, Phillip C. Yang, Gianluca Iaccarino, Ruike Renee Zhao
TL;DR
Existing amphibious millirobots often combine differently designed structures, while this paper develops a wireless magnetically actuated Kresling origami millirobot. The robot achieves rolling, flipping, and swimming across ground and liquid environments, with integrated multifunctional applications and ex vivo organ demonstrations.
Problem
Existing locomotion mechanisms require differently designed structures, while amphibious robots usually combine different structures.
Method
The paper uses a foldable Kresling shell with an internal cavity and twist-induced contraction, actuated through magnetic rotational motions.
Results
The robot achieves rolling, flipping, and swimming across ground and liquid environments, with integrated multifunctional applications and ex vivo organ demonstrations.
Takeaways & Limitations
The demonstrated robot supports adaptive multimodal locomotion and multifunctional applications across ground and liquid environments.
Takeaways & Limitations
Further research is needed on how fluid viscosity influences the robot’s swimming performance.
Abstract
from arXiv · showhide
Wireless millimeter-scale origami robots that can locomote in narrow spaces and morph their shapes have recently been explored with great potential for biomedical applications. Existing millimeter-scale origami devices usually require separate geometrical components for locomotion and functions, which increases the complexity of the robotic systems and their operation upon limited locomotion modes. Additionally, none of them can achieve both on-ground and in-water locomotion. Here we report a magnetically actuated amphibious origami millirobot that integrates capabilities of spinning-enabled multimodal locomotion, controlled delivery of liquid medicine, and cargo transportation with wireless operation. This millirobot takes full advantage of the geometrical features and folding/unfolding capability of Kresling origami, a triangulated hollow cylinder, to fulfill multifunction: its geometrical features are exploited for generating omnidirectional locomotion in various working environments, including on unstructured ground, in liquids, and at air-liquid interfaces through rolling, flipping, and spinning-induced propulsion; the folding/unfolding is utilized as a pumping mechanism for integrated multifunctionality such as controlled delivery of liquid medicine; furthermore, the spinning motion provides a sucking mechanism for targeted solid cargo transportation. This origami millirobot breaks the conventional way of utilizing origami folding only for shape reconfiguration and integrates multiple functions in one simple body. We anticipate the reported magnetic amphibious origami millirobots have the potential to serve as minimally invasive devices for biomedical diagnoses and treatments.
Main Text
The wireless amphibious millirobot uses a magnetically actuated Kresling origami body to combine adaptive rolling, flipping, and swimming across ground, liquid, and transitional environments. Its folding capability additionally enables controlled liquid delivery, while spinning supports solid-cargo transport and integrated biomedical operations.
- Multimodal locomotion: The robot automatically switches between rolling and flipping to overcome terrain obstacles while maintaining a designated travel direction and reducing control complexity.This self-adaptive behavior is demonstrated on ridges, stairs, potholes, walls, and rugged surfaces.
- Integrated functions: The Kresling shell couples rigid-body locomotion with reversible folding and unfolding to pump and release controlled doses of liquid medicine.This integrated navigation-and-delivery function is demonstrated in ex vivo stomach environments.
- Aquatic locomotion: 81.2 mm s-1 (11.9 body length s-1) is the maximum swimming speed for the robot with a hole and cuts at B = 10 mT and f = 30 Hz.The corresponding robot without the hole and cuts reaches 66.0 mm s-1 (9.7 body length s-1) under the same field.
- Integrated functions: The robot transports solid cargo across a hybrid terrestrial-aquatic route by switching among on-ground, underwater, and air-water-interface locomotion.It crosses a barrier, captures cargo underwater, releases it at a target, and returns over stairs and transitional zones.
- Multimodal locomotion: The triangulated cylindrical Kresling origami structure enables magnetically actuated rolling, flipping, and swimming across varied ground and liquid environments.These rotation-enabled modes provide adaptive locomotion in multiple terrains.
- Biomedical applications: The foldable internal cavity can integrate components such as mini cameras and forceps, supporting prospective endoscopy, biopsy, and other minimally invasive biomedical operations.Ex vivo animal-organ experiments indicate potential use in complex biomedical environments such as the gastrointestinal tract.
Materials and Methods
The millirobot is fabricated by folding a flower-shaped polypropylene Kresling pattern and attaching perforated Mylar hexagons, with magnetic plates providing actuation and folding control. Hydrophilic surface treatment, material composition, magnetic-field setup, and CFD simulations support amphibious operation and multifunctionality.
- Fabrication: The standard millirobot combines Kresling origami with one magnetic plate, whereas controlled liquid-medicine release uses two magnetic plates for folding.The magnetic plates consist of Ecoflex-0030 silicone embedded with 10 vol% NdFeB particles and 20 vol% glass bubbles.
- Fabrication: The Kresling sample is folded from a flower-shaped pattern cut from 0.05 mm thick polypropylene film.One side is treated with hydrophilic coating to distinguish hydrophobic outer and hydrophilic inner surfaces, facilitating water penetration.
- Magnetic Actuation: Locomotion is controlled by a uniform three-dimensional magnetic field generated by customized 3D Helmholtz coils within a 160 mm by 120 mm by 80 mm space.A 50 mm-diameter, 25 mm-thick N52 neodymium permanent magnet folds the Kresling for controlled liquid release.
- Computational Fluid Dynamics Simulations: Ansys Fluent CFD simulations qualitatively study how the robot’s frontal hole and radial cuts affect fluid behavior.Additional fabrication, material-characterization, and experimental-setup details are provided in the Supplementary Materials.