A few days ago, the Barcelona Institute of Technology (ICFO) published a discovery in Nano Letters: mixing nano-tungsten oxide particles with polyamide as a photosensitizer for color 3D printing can avoid the problem of discoloration in printing caused by traditional carbon-based photosensitizers , which contributes to the realization of high-fidelity 3D color printing.

In order to reduce cost and increase printing speed, selective sintering 3D printing usually incorporates photothermal sensitizers, which can accelerate the rate at which incident light is converted into heat. However, when printing white and color products, commonly used carbon-based photothermal sensitizers are used. Agents can cause discoloration of the work.

Previous ICFO related research has used gold-coated nanosilica microspheres to overcome the above problems (ie strong absorption in the near-infrared with minimal interaction with visible light). It turns out that while it works well in color printing, it has limitations when it comes to large gradation colorful high fidelity and pure white printing.

This time ICFO uses nano-tungsten oxide (WO3) as a photothermal sensitizer, which greatly reduces the production difficulty and material cost. It is colorless at high concentrations and has strong absorption in the near-infrared region, proving that they can convert light into heat at a very fast rate, making them a fast flux; UV light is effectively activated or deactivated; more importantly, they are stable at very high temperatures and have shown superior heating to color change rates compared to other sensitizers available. 

Finally, when mixed with other color inks, these nanoparticles were able to reproduce the same color as the original powder, maintaining the color purity of the original sample. This also opens up a new avenue for high-fidelity 3D color printing.