Countering counterfeiters
An NUS Engineering team consisting of (from left) Asst Prof Qiu, Dr Teng and NUS ECE Research Fellow Dr Huang Kun has developed a nanophoton sieve for document authentication (Photo: Lianhe Zaobao © Singapore Press Holdings Ltd)
Lawbreakers may soon have to contend with a higher level of security enabled by technology designed by an NUS Engineering team. The researchers' breakthrough allows users to view complex holograms that are almost impossible to replicate.
As a result of the ultracapacity nanophoton sieve developed by the scientists, users may now employ customised holograms that integrate data of different dimensions, display distance, polarisation and wavelength as means of authenticating documents. The sieve can be used in a handheld device that reveals these high-pixel, high-quality holographic images.
This innovation, featured in Nature Communications in May 2015, opens up the possibility of combining many specifications in the design of sophisticated holograms to encrypt an optical "message, said NUS Electrical and Computer Engineering (ECE) Assistant Professor Qiu Cheng-Wei, who led the team. Such holograms offer nanoscale-precision security unlike watermarks, magnetic stripes, electronic chips or barcodes. The more commonly used authentication methods can be easily replicated, as their features are mostly visible to the naked eye.
The nanophoton sieve, a thin plate measuring 0.15mm by 0.15mm, has the capacity to incorporate more than 34,000 nanoholes randomly distributed on its surface, explained Asst Prof Qiu.
The ultracapacity nanophoton sieve, measuring 0.15mm by 0.15mm (Photo: Lianhe Zaobao © Singapore Press Holdings Ltd)
He said, "This innovation fits well into certain niche end-users who wish to pay extra fabrication cost to guarantee the advanced security. Nano-lithography equipment was used in the fabrication of the sieve, which was assisted by Dr Teng Jinghua, Principal Scientist and Head (Patterning & Fabrication) at the Institute of Materials Research and Engineering.
"So far, I don't see any effective hologram-based technology as document authentication. Even if there may be some, ours is the most state-of-the-art, since our hybrid design method can handle the sizes and positions of many nanoholes using biology-inspired evolution algorithm, Asst Prof Qiu added, explaining that the algorithm that positioned the nanoholes was inspired by biological processes in nature.
As the next step of its research, the researchers will work on making its system more robust and developing intricate holographic images of higher pixels. It will also test other emerging applications enabled by the technology. The team is also developing methods to speed up fabrication and lower costs.
NUS has started talks with industrial partners to commercialise the patent-pending technology.
