From pixels to voxels: A mechanistic perspective on volumetric 3D-printing

The introduction of chemical and/or optical nonlinearity to 3D-printing has paved the way towards volumetric 3D-printing, enabling remarkable advancements in speed, resolution, and the fabrication of previously inaccessible materials. Given the growing interest of the scientific community, we present a critical review that aims to provide a comprehensive discussion of the potential of volumetric 3D-printing. First, the theoretical framework of photopolymerization is summarized. Subsequent sections highlight the progression of light-based 3D-printing from traditional to emerging volumetric 3D-printing techniques, encompassing both single- and multi-photon polymerization. Special attention is given to the rapidly advancing subfield of volumetric bioprinting which holds great promise for the fabrication of complex multi-material tissue constructs. Finally, critical considerations and limitations of volumetric 3D-printing as well as prospective solutions and opportunities for future research are discussed to allow readers to appreciate and participate in the exciting and rapidly advancing field of volumetric 3D-printing.