Magnetically assisted direct writing 3D printing programmable magnetically responsive origami actuator

Abstract

Magnetically responsive origami actuators have significant potential in soft robotics and biomedicine, but their development is limited by complex preparation processes, limited material compatibility, and a single deformation mode. In this study, we propose an innovative strategy to achieve synergistic regulation of magnetic domain space programming and structural stiffness gradient by integrating magnetically-assisted direct-write 3D printing technology and notch design. The novel magnetic ink developed based on PDMS/Ecoflex elastic matrix and neodymium-iron-boron (NdFeB) magnetic particles, combined with the real-time magnetic field orientation technology, enables accurate programming of the magnetic moment directions during the printing process to construct complex magnetic domain distributions. The introduction of the notch structure significantly reduces the local stiffness and concentrates the deformation on the pre-programmed creases, improving driving efficiency. By combining the multi-axis magnetron platform with origami geometries (e.g., Miura, Kresling, and jig origami configurations), the actuator exhibits multi-modal deformation capabilities such as reversible folding, rolling, and metamaterial shrinkage. Experiments and simulations show that the notch design improves the bending angle of the actuator by a factor of 2.8 under a 50 mT magnetic field compared to the non-notched structure. In addition, the functionalized application verification includes clamping (8 g load), bionic pumping (7.8 mL of liquid per pumping cycle), and adjustable stiffness loading (10 g capacity), highlighting its applicability in soft robotics and microfluidic systems. This study provides a mold-less and scalable fabrication platform for high-precision magnetically driven origami structures, which promotes the development of smart devices toward multimodal actuation and functional integration.