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Alexander Powell

ICFO - The Institute of Photonic Sciences

Utilising Nanotechnology to achieve bright and colourful powder sintering

Selectively sintering a powdered material via optically induced heating is one of the most important additive manufacturing techniques today, however this procedure can be slow and costly compared to conventional processing methods. To overcome this, the polymer powders used in selective sintering are often mixed with strongly optically absorbing additives, which act as photothermal sensitizers (PTS) by heating up significantly more than the surrounding polymer upon illumination. This allows for faster powder fusion or sintering, and has recently led to the development of several low-cost selective laser sintering printers, and to new 3DP approaches, such as High-Speed Sintering and Multi-Jet Fusion. However, due to the broad absorption spectrum of the carbon-based PTS varieties reported thus far, printed objects turn out black or grey in colour. This makes it impossible to produce brightly-coloured parts without extensive post processing steps, which significantly limits their utility for end users where aesthetics are important. A photothermal sensitizer with low absorption in the visible, yet supporting a strong resonant absorption in the near-to-mid infrared is required to produce white or coloured 3D objects using this method.

In this presentation, we demonstrate the use of plasmonic nanoparticles as nano-engineered photothermal sensitizers. These nanoparticles are shown to be highly efficient light-to-heat converters compared to the industrial standard carbon black, and their localized surface plasmon resonances produce strong absorption peaks which can be tuned to the near infrared by engineering the size, shape and chemistry of the nanoparticles, leaving minimal absorption in the visible. We demonstrate that this enables the production of functional, white 3D objects via selective sintering with low-power, low-cost diode lasers, with minimal impact to the aesthetic properties of the powder and the finished shape. Furthermore, through the addition of coloured dyes, we can produce bright, multi-colour 3D objects. In this presentation we showcase the development of this technology, our current state-of-the-art, and the potential functionalities of nanotechnology-based 3D printing in a variety of industrial sectors.


Alex studied physics at Durham University and then completed a PhD in materials science at the University of Oxford, where he was awarded the EPSRC postdoctoral prize fellowship to continue his research into novel nanoscale sensors. He later moved to the Institute of Photonic Sciences in Barcelona where he pursues research into utilising nanotechnology for 3D printing.


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