A state-of-the-art review of 4D printing techniques, stimuli activated materials and future perspectives

Abstract

In recent years, 4DP has gained significant interest in the field of AM, functional prototyping, soft robotics, biomaterials, pharmaceutical, and textiles. 4DP is an AM technique that integrates 3DP with stimuli-responsive materials. When exposed to various external stimuli, such as temperature, light, pH, magnetic field, electricity, and moisture; the structures formed by 4DP technique are space time dependent and can change their shape and/or properties over the period of time. Herein, this overview presents stimuli activated smart materials used in 4DP, 4DP techniques and practical applications of 4D printed smart structures. This overview also elucidates challenges and future perspectives in terms of, synthetization of different polymers, multi material printing, sustainability, pre-programming knowledge, and latent applications of 4D printed structures.