Nanomagnetic encoding of shape-morphing micromachines

• Published in: Nature (London) Vol. 575; no. 7781; pp. 164 - 168
• Main Authors: Cui, Jizhai, Huang, Tian-Yun, Luo, Zhaochu, Testa, Paolo, Gu, Hongri, Chen, Xiang-Zhong, Nelson, Bradley J., Heyderman, Laura J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2019; Nature Publishing Group
• Subjects: 142/126; 639/166/988; 639/301/1005; 639/766/25; 639/925/927/1062; Anisotropy; Automation; Birds; Configurations; Design; Design and construction; Fabrication; Flapping; Genetic transformation; Hovering; Humanities and Social Sciences; Magnetic fields; Magnetic properties; Magnetism; Manufacturing engineering; Materials; Metamaterials; Microelectromechanical systems; Modular units; Morphing; multidisciplinary; Nanotechnology; Robotics; Robots; Science; Science (multidisciplinary); Shape-memory alloys; Spatial distribution; Structural design; Structural engineering; Task complexity; Switzerland
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-019-1713-2

Shape-morphing systems, which can perform complex tasks through morphological transformations, are of great interest for future applications in minimally invasive medicine 1 , 2 , soft robotics 3 – 6 , active metamaterials 7 and smart surfaces 8 . With current fabrication methods, shape-morphing configurations have been embedded into structural design by, for example, spatial distribution of heterogeneous materials 9 – 14 , which cannot be altered once fabricated. The systems are therefore restricted to a single type of transformation that is predetermined by their geometry. Here we develop a strategy to encode multiple shape-morphing instructions into a micromachine by programming the magnetic configurations of arrays of single-domain nanomagnets on connected panels. This programming is achieved by applying a specific sequence of magnetic fields to nanomagnets with suitably tailored switching fields, and results in specific shape transformations of the customized micromachines under an applied magnetic field. Using this concept, we have built an assembly of modular units that can be programmed to morph into letters of the alphabet, and we have constructed a microscale ‘bird’ capable of complex behaviours, including ‘flapping’, ‘hovering’, ‘turning’ and ‘side-slipping’. This establishes a route for the creation of future intelligent microsystems that are reconfigurable and reprogrammable in situ, and that can therefore adapt to complex situations. A micromachine less than 100 micrometres across, made of arrays of nanomagnets on hinged panels, is encoded with multiple shape transformations  and actuated with a magnetic field.