A review of 4D printing of hydrogel in biomedical implant applications

Currently, 3D printing has emerged in the biomedical implants in fracture fixations as well as artificial organs. Interestingly, 4D bioprinting is a recently developed method or concept that intends to logically create 3D patterned biological matrices from synthetic hydrogel-based inks with the potential to change form upon stimulation. However, the static and fixed structure of 3D printing unable to mimic the complex structures of human tissue which involves contract and relax. In addressing this issue, the additive manufacturing (AM) of four dimensional (4D printing) has taken a place in biomedical application in fabricating highly printable shapes.