One method of 3D printing is to selectively expose liquid resin to ultraviolet  (UV)  light to harden the resin into a solid. Now, scientists  

have  developed a new resin  that can  use safer  and more  energy-efficient visible light. Although visible light can already  be used on 

photosensitive resins,  the hardening process is quite slow, so it is not practical in actual use. Ultraviolet light works much faster, but its 

energy requirements-so its cost is much higher.

In addition, excessive ultraviolet rays may harm biological tissues. This means that it cannot be used for bioprinting of tissues contain

living cells, nor can be used for printing internal structures of the human body.  Ultraviolet rays cannot penetrate the resin like visible  

light,  and it also scatters more. Considering these  limitations, researchers  from the University of Texas at Austin  have  developed a 

new resin,  which  consists of monomers,  photo-oxygen  catalyst  (PRC),  two co-initiators  and  an opaque agent. composition.

The PRC absorbs the visible  light of the  LED on the printer, which  promotes the transfer of  electrons  between  coinitiators.  This in 

turn causes the monomer to polymerize (harden).  Opacifiers help to limit the process to areas exposed to light and improve printing 

resolution.

The fastest  printing speed of 1.8 inches (46 mm) per hour is practical for small items, but it  still less than half of the maximum speed 

of UV printing. In other words, this number can be increased by increas the intensity of visible light or adding  additional compounds 

to the resin.