Research on Microwave-Induced Bidirectional Deformation of Coix Seed Compound Materials in 4D Printing

The traditional 4D deformation of 3D printed objects has certain limitations, because the deformation they achieve is often singular. Unlike previous 4D deformation studies, we proposed a new method to achieve bidirectional 4D deformation of 3D printed objects and explored the principles that lead to this change. We chose the paste made of coix seeds and purple potato powders as the printing ink, and tested its rheological properties, moisture distribution, and dielectric properties to predict and explain the characteristics of the 4D printing process. A model-based structural design was performed to study the conditions needed to achieve bidirectional 4D deformation. Experiments showed that the local expansion of the microwave-induced printed object was the driving force that led to the deformation. The structure of the deformable component in the model changed the role of this driving force. Different 4D deformation effects can be achieved by adjusting the structure of the model. The experiment also proved that the composition of the printing ink did affect 4D deformation. The purpose of this research is to provide a method to accentuate the 4D deformation effect, so that users can obtain a more appealing visual experience, and such deformation will attract children to consume, which can then be applied to the manufacture of cold food dishes and the production of food for children.