Harnessing near-infrared light for advanced 3D printing

Abstract

Light drives the curing process in many 3D printing strategies. To broaden the horizons of 3D printing, there is an ongoing push toward longer wavelengths for more effective, gentle, and precise layer photocuring of materials containing fillers or biological substances. Harvesting near-infrared (NIR) light (750–2500 nm) is at the forefront of this endeavour. Multiphoton lithography makes use of infrared light and is an established 3D printing technology, but it does require femtosecond pulse lasers. On the other hand, affordable NIR light sources can be used to 3D print objects with high precision, cytocompatibility, greater functionality, and from a wide range of polymers, but their implementation is not straightforward. In this review, recent studies are presented that advance the field of 3D printing with NIR light. Several cutting-edge technologies are identified, including support-free direct-ink-writing, in vivo bioprinting, and volumetric multimaterial modification, with a final perspective offered on volumetric projection printing toward high-throughput production.