4D Printing Magnetically Activated Shape Morphing Objects

Abstract

Magnetic Soft (shape memory) Materials (MSM for short) are a form of shape memory hybrid in which the shape change is initiated by magnetic particles embedded in an elastomer matrix. When an external magnetic field is applied, these magnetized particles will align themselves to this magnetic field, straining the elastomer in a specific shape. Once the magnetic field is removed, the elastic properties of the elastomer pull the object back to its original shape.
This report describes the work done on the development of a 4D printer, in which the shape change of the MSM objects is programmed during manufacturing by controlling the orientation of the pre-magnetized particles in the still uncured silicone. An external dual extrusion system is used to mix a two component silicone during 4D printing, so that the material cures upon hitting the build plate, while staying liquid during printing. The goal of developing a reliable system capable of extruding and printing the highly viscose magnetic material was however not achieved, as the extrusion motors lacked the needed force and the system was not rigid enough to deal with the high pressures involved. Adoption of a new printer design in which the path from extruder to build plate is severely limited is recommended.
In addition, a literature review has been conducted into applications of generic shape memory materials (SMM), metamaterials and magnetic soft materials with the purpose to draw inspiration from proposed applications of these materials for a novel MSM application design. It was found that MSM applications showed many overlaps with SMM and metamaterials, but that there were also some gaps in the reported application proposals of MSM where SMM and metamaterials are currently used for. MSM could be a valuable material used for (haptic) communication and texture change. More (indirect) relations with MSM, SMM and metamaterials have been identified which could serve as inspiration for future projects.
Lastly, a novel demonstrator concept design has been developed that shows the unique fast and multi-directional characteristics of MSM, using the findings of the literature review and the use of the Material Driven Design method. With additional input from peer students in a workshop, the idea of a 3-way changing texture is proposed. This texture utilizes specific magnetization patterns in an array of MSM actuators to generate two texture variations depending on the direction of the applied magnetic field, in addition to a neutral state when the field is removed. Its feasibility is proven by small scale prototypes.
This project has been the second time this material has been researched at the Faculty of Industrial Design Engineering at the Delft University of Technology, building upon previously delivered work and paves a path for further iterations on manufacturing and design of applications of the magnetic soft material.