Fabrication of Biocompatible Helical Fibers Using an Optical Vortex Beam

Helical structures are a fundamental characteristic of biological tissues, yet helical biomaterial scaffolds remain underdeveloped. Optical vortex beams, a unique class of light with helical wavefronts, carry optical angular momentum (OAM). Interestingly, it has been discovered that the OAM of optical vortex beams twists the irradiated photocurable resins to form helical fiber structures. This phenomenon opens up new possibilities that optical vortex beams enable the creation of photopolymerized structures for tissue engineering scaffolds. However, the fabrication of helical fibers formed of biocompatible polymers has not been established yet. In this study, we successfully fabricated helical gel fibers using poly(ethylene glycol) (PEG), a representative biocompatible polymer, through photopolymerization with an optical vortex beam. The helical wavefront of the optical vortex beam enabled the creation of twisted PEG gel microscale fibers with minimal branching, likely due to the OAM transferred to the gel precursors during photopolymerization. In contrast, PEG gel microscale fibers fabricated using a Gaussian beam with a planar wavefront exhibited significant branching. These findings demonstrate the potential of optical vortex beams for fabricating helical structures with biocompatible polymers, offering a promising approach for applications such as helical tissue engineering.