Emerging trends in 4d printing of hydrogels in the biomedical field: A review

Currently, 4D printing is widely known in additive manufacturing for the fabrication of customizable objects with a high level of complexity and cost-effectiveness. As an emerging technique in AM technology, 4D printing can replicate a product with any physical and mechanical flexibility over time for biomedical fields. Aside from metals, hydrogel-forming polymers, including biopolymers, synthetic polymers, and nanocomposites, have been extensively explored in 4D printing technology. This review aims to emphasize the potential, depth of insight, and viability of the hydrogels fabricated using 4D printing, which is employed in various biomedical fields. The 4D able to integrate with the microenvironment of human body and can be on of an advance method in medical field. Recent advances in their applications were then summarized. Finally, the outlook on future perspectives and challenges of hydrogel-based 4D printing were also presented.