Exploring the evolution of 5D and 6D printing: Current progress, challenges, technological innovations, and transformative biomedical applications

The evolution of additive manufacturing (AM) has led to the development of 4D printing, enabling 3D printed structures to dynamically alter shape in response to external stimuli, thereby improving mechanical properties and patient-specific applications. However, limitations persist in achieving complex geometry elements with high mechanical strength. To address these challenges, enhancement in the printing process and the use of multi-responsive smart materials are essential. The emergence of 5D printing, which combines additive and subtractive manufacturing, has advanced medical design by enhancing structural integrity and surface quality. As AM technology continues to evolve, 5D and 6D printing represent breakthroughs in biomedical engineering. By integrating the dynamic adaptability of 4D printing with the precision of 5D printing, 6D printing offers the potential for patient-specific interventions, particularly in biomedical applications. This review article evaluates the progress made in developing AM technologies, particularly 5D and 6D printing, highlighting the significant growth in healthcare due to the development of materials and technologies that respond to specific clinical demands.