Colourful 3D anti-counterfeiting label using nanoscale additive manufacturing

Microprinting is changing anti-counterfeit technology by producing complex micro-/nano-scale labels to increase the security level. However, the current microprinted anti-counterfeiting labels only contain 2D features, thought of as single coding (e.g. mostly in texts or graphs), unable to satisfy the high-end anti-counterfeiting demands of producing multi-coding, high-storage-density labels. Here, we introduce an approach for fluorescence printing to produce a 3D colourful, sophisticated anti-counterfeiting label. In the method, pre-synthetic QDs are printed with photoresists based on two-photon polymerisation, allowing for accurate regulation of fluorescence in both 2D and 3D. The fabricated photoresists exhibit immediate and postprocessing-free colour emissions under UV light. We demonstrated the ultra-high free design and accurate manufacturing capability of the approach by fabricating multi-colour, multi-layer patterns containing both texts and graphs on a 50μm × 50μm × 30μm portable label. The approach can also be applied to multi-dimensional optical data storage and colourful microdisplays.