Magnetic actuation enables fast, wireless, and safe operation of soft actuators [1,2]. Additive manufacturing allows the creation of magneto-active composites in complex, bioinspired shapes [3]. The impressive migratory capabilities of monarch butterflies, enabled by their efficient wing structures, serve as inspiration for bioinspired soft robots and micro-aerial vehicles. This study introduces the design, fabrication, and wing-morphing behavior of 3D-printed magnetic butterflies, emphasizing optimal material and design parameters to replicate the natural wing-morphing of monarchs [4]. Using a composite of thermoplastic polyurethane and micron-sized Nd₂Fe₁₄B magnetic powder, 12 distinct butterfly designs—varying in size, vein patterns, and stiffness—are produced through powder bed fusion (PBF) 3D printing, yielding a total of 84 specimens. These lightweight specimens, which require minimal post-processing, have weights per unit area of approximately 270, 480, and 1045 g/m² for small, medium, and large sizes, respectively.

Deformation is induced in the specimens using a permanent magnet, effectively mimicking monarch butterflies without the need for embedded electronics. A combined approach of finite element simulations and experimental analysis explores how size, geometric features, and laser energy scale influence wing morphing. Lower laser energy scales produce porous specimens with rapid bending capabilities, while higher energy scales result in structures with greater mechanical strength and diverse deformation patterns. Additionally, vein structures enhance morphing performance.

This work was financially supported by the Deutsche Forschungs- gemeinschaft (DFG, German Research Foundation), Project ID No. 405553726, TRR 270, and the RTG 2761 LokoAssist (grant no. 450821862).

References
[1] Y. Kim, X. Zhao, Chemical reviews, 2022, 122(5), 5317-5364.
[2] X. Wang, G. Mao, J. Ge, M. Drack, … D. Makarov, Communications Materials, 2020, 1(1), 67.
[3] K. Schäfer, M. Lutzi, M.B. Khan, … O. Gutfleisch, Additive Manufacturing, 2024, 79, 103905.
[4] M.B. Khan, K. Schäfer, … O. Gutfleisch, Advanced Intelligent Systems, 2024, 2400620.