While there have been recent advances in 3-D printing of the incredibly light yet strong material graphene aerogel (the least dense solid known, at 160gm/m³), achieving complex structures has been elusive and hampered
realising the material’s full potential.

To date, 3-D printing of graphene aerogel has been done using direct-ink or other extrusion-based methods, restricting the design of parts printed from this ultra-low-density material to simple geometries.

To overcome this limitation, for two years scientists and engineers at Lawrence Livermore National Laboratory (LLNL) (www.llnl.gov) and Virginia Tech (both in the USA) have focused on 3-D printing this material using light — a method known as projection micro-stereolithography.

In a paper published on-line, the team reported a breakthrough, producing ‘micro architectured’ 3-D graphene aerogel structures with higher resolution and complexity than anything created before with other 3-D printing methods.

According to LLNL principal investigator Marcus Worsley, researchers began pursuing alternative printing methods while working to optimise electrodes for flow batteries; and to reach the level of intricacy required for the project, it was clear that the team needed a different approach.

In projection micro-stereolithography, ultra-violet light is used to project an image of a part layer into a photo-sensitive liquid resin, which is cured and hardened into the shape of the image.

Using this method, researchers were able to reduce the resolution in 3-D graphene aerogels printed through extrusion-based methods from around 100µm to about 10µm.