Scientists at Heriot-Watt University in Edinburgh have created an innovative 3D printing technique using near-infrared (NIR) light. Led by Dr Jose Marques-Hueso, the team developed a method that enables the printing of complex structures with multiple materials and colours.
Traditional 3D printers use a blue or UV laser to solidify a liquid resin and build objects layer by layer. However, integrating different materials has been a challenge.
The scientists at Heriot-Watt University used a NIR light source that can penetrate the resin vat to a depth of over 5cm without the need for layering.
This breakthrough opens up opportunities for industries relying on specialized parts, such as healthcare and electronics.
A unique 3d printing method
Dr Marques-Hueso explained the novelty of their method, stating that they utilize the NIR invisibility windows of materials to print at greater depths.
This means that a single material can be printed, and a second material can later be added anywhere within the 3D space.
The NIR laser can penetrate through the previous material,
making it appear transparent and allowing the addition of a different material inside.
The project also involved the development of engineered resins containing nanoparticles that exhibit optical upconversion. These nanoparticles absorb NIR photons and convert them into blue photons, solidifying the resin. The process is non-linear, allowing the NIR to penetrate deep into the material and solidify only the desired portions.
The pros of it: NIR laser
The new technique enables the printing of multiple materials with distinct properties in a single sample. For example, flexible elastomers and rigid acrylic can be combined, making them valuable for businesses like shoe production. The possibilities include printing objects inside cavities, repairing broken objects, and even bioprinting through the skin.
Another benefit of this technology is its affordable price. The entire mechanism, according to Dr Marques-Hueso, may be constructed for less than £400. Due to the particular materials used, this technique can use inexpensive lasers as opposed to other laser-based technologies that demand expensive ultrafast lasers.
The project received £280,000 in funding from the Engineering and Physical Sciences Research Council (EPSRC) and was titled “Multimaterial Stereolithography by Crosslinking through Luminescence Excitation.”
The team hopes to collaborate with businesses to further develop this promising technology.
The findings have been published in Applied Materials Today.
