Development of 4D printing and its performance testing methods

Abstract 4D printing is a cutting‐edge additive manufacturing technology that introduces the time dimension, allowing printed objects to have dynamic, changeable properties, functions or shapes. Compared to traditional 3D printing, 4D printing can create complex geometric structures and respond to stimuli such as temperature, humidity, light, or magnetic fields. These characteristics make it highly promising for applications in fields such as aerospace, biomedicine, and soft robotics. However, performance testing and analysis for 4D printing technologies have not yet been standardized. Herein, an overview of 4D printing performance testing methods are presented. Initially, the molding methods of 4D printing are discussed. Next, the shape memory recovery testing methods for bending deformation models, tensile models and compression models are reviewed. Through analyzing the model designs and experimental methods, the methods for measuring key performance parameters such as shape memory recovery rate, fixation rate, and shape memory recovery force are summarized. Finally, the development directions of 4D printing are highlighted, including the exploration of new materials, the development of multifunctional structures, and the establishment of more standardized testing methods to promote its deeper application and technological improvement across various fields.