Advances in extrusion-based bioprinting enabled by advanced printhead and nozzle designs.

3D printing is a rapidly evolving technology that enables new applications in biomedical engineering. In particular, its role in the fabrication of complex living tissues and multimaterial structures that support living cells opens new possibilities for biomaterial processing as well as potential clinical applications. Among the various 3D printing modalities developed over recent decades, extrusion-based printing shows particular promise for bioprinting and a number of successful examples are highlighted in this review. However, despite its widespread adoption, extrusion-based 3D printing is constrained by the limited range of viscoelasticities that can be processed, certain inefficiencies in multi-material printing, restricted spatial resolution and fundamental trade-offs between printing speed and cell viability in bioprinting applications. Here, we present a comprehensive review of existing printhead designs for extrusion-based 3D printing, with a specific focus on biomedical applications. We highlight recent technological breakthroughs, identify persistent bottlenecks and propose strategic directions for next-generation printhead development aimed at overcoming current limitations. Our goal is to catalyze innovation in printhead engineering for biomedical applications to enable the fabrication of structures that are still unattainable with current extrusion-based 3D printing systems.