Four-Dimensional (4D) Printing: Applying Soft Adaptive Materials to Additive Manufacturing

Four-dimensional (4D) printing is an up-and-coming technology for the creation of dynamic devices which have shape changing capabilities or on-demand capabilities over time. Through the printing of adaptive 3D structures, the concept of 4D printing can be realized. Modern manufacturing primarily utilizes direct assembly techniques, limiting the possibility of error correction or instant modification of a structure. Self-building, programmable physical materials are interesting for the automatic and remote construction of structures. Adaptive materials are programmable physical or biological materials which possess shape changing properties or can be made to have simple logic responses. There is immense potential in having disorganized fragments form an ordered construct through physical interactions. However, these are currently limited to only self-assembly at the smallest scale, typically at the nanoscale. The answer to customizable macro-structures is in additive manufacturing, or 3D printing. 3D printing is a 30 years old technology which is beginning to be widely used by consumers. However, the main gripes about this technology are that it is too inefficient, inaccessible, and slow. Cost is also a significant factor in the adoption of this technology. 3D printing has the potential to transform and disrupt the manufacturing landscape as well as our lives. 4D printing seeks to use multi-functional materials in 3D printing so that the printed structure has multiple response capabilities and able to self-assemble on the macroscale. In this paper, we will analyze the early promise of this technology as well as to highlight potential challenges that adopters could face. The primary focus will be to have a look at the application of materials to 3D printing and to show how these materials can be tailored to create responsive customized 4D structures.