Research into 4D printing has attracted unprecedented interest since 2013 when the idea was first introduced. It is based on 3D printing technology but requires additional stimulus and stimulus-responsive materials. Based on certain interaction mechanisms between the stimulus and smart materials, as well as the appropriate design of multi-material structures from mathematical modelling, 4D printed structures evolve as a function of time and exhibit intelligent behaviour. Unlike 3D printing, 4D printing is time-dependent, printer-independent, predictable, and targets shape/property/functionality evolution. This allows for self-assembly, multi-functionality, and self-repair. This paper presents a comprehensive review of the 4D printing process and summarizes the practical concepts and related tools that have a prominent role in this field. Unsought aspects of 4D printing are also studied and organized for future research.
Source: Science Direct