3D printing method could open up path to new metamaterials

‘Currently, there is no real three-dimensional fabrication method on the nanoscale,’ said lead investigator Joachim Fischer of the Karlsruhe Institute of Technology (KIT). ‘The only thing you can do is you can stack two-dimensional stuff on top of each other, which is very time consuming and error prone.’

The team’s method is a variation of the relatively new 3D additive manufacturing technique of two-photon polymerisation (2PP).

Here, a liquid resin — or ‘photoresist’ — is polymerised at certain points by a pulsed laser, leaving behind 3D features as a solid polymer.

However, the minimum resolution in which features can be created is around 100nm in the lateral plane and 250nm in the axial plane, which does not meet the strict definition of nanoscale.

The team developed a technique that uses two lasers: an excitation laser to start polymerisation and a depletion laser to almost immediately stop it, thus limiting the size of the resultant features.