Emerging paradigms in 3D bioprinting: A critical review of volumetric, embedded, and multi-material fabrication for biomedical applications

Three-dimensional (3D) printing has advanced additive manufacturing by enabling the fabrication of complex, application-specific structures across biomedical, pharmaceutical, and industrial fields. However, conventional layer-by-layer deposition presents inherent limitations, including slow production rates, material constraints, and structural inconsistencies. This review critically evaluates recent innovative developments in advanced 3D bioprinting/biofabrication technologies, namely Volumetric Additive Manufacturing (VAM), Freeform Reversible Embedding of Suspended Hydrogels (FRESH), and Embedded Multi-Material Extrusion Bioprinting (EMMB), which introduce novel fabrication strategies to overcome these limitations. Techniques are examined in terms of their working principles, material compatibility, resolution, structural fidelity, and suitability for tissue engineering, drug delivery, and regenerative medicine. The review also addresses ongoing challenges, including bioink optimization, interfacial control in multi-material systems, and achieving scalability without compromising functionality. Future perspectives include the integration of hybrid manufacturing, artificial intelligence (AI) for real-time process optimization, and microscale fabrication strategies targeting medical microdevices and micro-electro-mechanical systems (MEMS). By providing a comparative overview of conventional and emerging 3D printing techniques, this work outlines a path toward the next generation of high-precision, multifunctional biofabrication platforms capable of supporting personalized therapeutic solutions and complex prototyping across diverse domains.