University of Texas at Austin (UTA) scientists have developed a new method to rapidly 3D print objects using visible light.
Most 3D printers use high-energy ultraviolet (UV) light to cure liquid resins into solid objects. Being able to use visible light for curing could reduce costs, improve biocompatibility, allow greater depth of light penetration and reduce light scattering – something UV light hasn’t been really good at.
Many scientists have spoken about the merits of using visible-light curing for 3D printing soft robotics, but this process is excruciatingly slow.
Now a team led by UTA assistant professor Zachariah A Page has developed new photopolymer resins that could help boost the speed of visible-light curing.
Reporting their findings in ‘ACS Central Science’, the scientists developed violet-, blue-, green- and red-colored resins that contained a monomer, a photoredox catalyst (PRC), two co-initiators and an opaquing agent.
When the PRC absorbed visible light from LEDs, it catalyzed the transfer of electrons between the co-initiators, which generated radicals that caused the monomer to polymerize.
The opaquing agent on the other hand helped confine curing to the areas struck by light, which improved spatial resolution.
According to the scientists, the optimized mix of components allows them to print stiff and soft objects with small features (less than 100 μm), mechanical uniformity and build speeds up to 1.8 inches per hour.
The scientists however caution that the best build speed is still less than half that of the fastest rate obtained using UV light.
This could nevertheless be improved by increasing the light intensity or adding other components to the resin, says Page.
Image and content: ACS Central Science/ACS