Near-infrared creates complex 3D structures with multiple materials and colours

The group, led by Dr Jose Marques-Hueso from the Institute of Sensors, Signals & Systems, achieved this by modifying stereolithography to enable multi-material integration. A conventional 3D printer would normally apply a blue or UV laser to a liquid resin that is then selectively solidified in layers to build an object. A drawback of this approach, however, has been the limitations in intermixing materials.

In an EPSRC-funded project dubbed MUSCLE (MUltimaterial Stereolithography by Crosslinking through Luminescence Excitation), the scientists have used a NIR light source capable of printing at far greater depths into the resin vat without the need to print in layers.

According to Heriot-Watt, the findings present opportunities for industry, particularly those that rely on specialist parts such as in health and electrical sectors.

In a statement, Dr Marques-Hueso said: “The novelty of our new method, which has never been done before, is to use the NIR invisibility windows of materials to print at a depth of over 5cm, whereas the conventional technology has a depth limit of around 0.1mm. This means that you can print with one material and later add a second material, solidifying it at any position of the 3D space, and not only on top of the outer surfaces.