Mechanically‐Guided 4D Printing of Magnetoresponsive Soft Materials across Different Length Scale

Abstract

Untethered magnetoresponsive soft materials that can transform between various complex 3D shapes are of growing interests in diverse areas such as soft robotics, flexible electronics, and biomedical engineering. Previous approaches are difficult to precisely encode continuous 3D magnetization profiles in smallscale 3D structures. Herein, a novel method to produce magnetoresponsive soft materials for shape-morphing systems across different length scale is reported. The magnetization profiles are programmed by the mechanically-guided 4D printing with high precision and time-cost efficiency. A theoretical model and model-based simulation method are developed to quantitatively predict shapemorphing of printed structures under applied magnetic fields, and guide the design of complex 3D shapes. A broad set of structures with complex transformations are fabricated to illustrate the capability of the methods. Diverse typical functional applications from centimeter-to millimeter-scale, including soft crawling robots, flexible grippers, bionic butterfly, and multistate magnetic switch, are further demonstrated.

Octopus‐Inspired Adaptable Soft Grippers Based on 4D Printing: Numerical Modeling, Inverse Design, and Experimental Validation

“…The residual stress remains in printed structures due to the repeated stretch and storage from the heating and cooling cycles during the 3D printing, providing an opportunity to control the programming of soft grippers. [ 35 ] Therefore, the 4D printed PLA bilayer structures will shrink and recover under thermal stimulus without an extra program process. The thermal shrinkage of the bilayer structure was modeled with the coefficient of thermal expansion (CTE) difference between the top and bottom layers.…”

“…Most proposed stimuli‐responsive soft grippers only used actuators with a single deformation pattern, usually pure bending, to grasp objects. [ 20–22,24,26–29,31,35,36 ] Figure 3b shows the comparison of the reachable workspace between an octopus‐inspired gripper and a pure‐bending soft gripper. The octopus‐inspired gripper and the pure‐bending soft gripper have the same length for comparability, where the length of an octopus‐inspired gripper refers to R + L .…”

An experimental investigation of dynamic motions of a small-scale magnetoactive soft robot undergoing large nonlinear movements

“…In addition, MSRs offer large deformation capacity due to their relatively low elastic modulus, which allows functionality in bifurcated environments such as arteries in the human body. Magnetoactive soft robots, consisting of hard ferromagnetic particles such as neodymium-iron-boron (NdFeB) suspended or arranged in a soft elastomeric matrix, are usually fabricated through molding [4], lost wax casting [5] and 4D printing [6]. Zhu et al [6] developed a 4D printing approach to encode continuous 3D magnetization patterns within various magnetic structures.…”

“…Magnetoactive soft robots, consisting of hard ferromagnetic particles such as neodymium-iron-boron (NdFeB) suspended or arranged in a soft elastomeric matrix, are usually fabricated through molding [4], lost wax casting [5] and 4D printing [6]. Zhu et al [6] developed a 4D printing approach to encode continuous 3D magnetization patterns within various magnetic structures. Zhang et al [7] developed a 4D printing strategy on the basis of traditional 3D injection printing to generate particular magnetization profiles for programmable transformation and controllable locomotion of MSRs.…”

A Power Compensation Strategy for Achieving Homogeneous Microstructures for 4D Printing Shape-Adaptive PNIPAM Hydrogels: Out-of-Plane Variations

“…Moreover, 4D printing typically shows a low printing speed, especially when it uses a laser for line-wise scanning. Therefore, it is of importance to achieve the corresponding material properties for simulations, before performing experiments [ 22 ], which requires homogeneous samples for testing, as well as verifying the deformations achieved via experiments. There is a lot of literature on the aberration and absorption of two-photon polymerization/absorption, separately [ 19 , 23 , 24 , 25 , 26 ].…”