HKU presents microscale 3D printer for anticounterfeiting labels

According to the team, led by Dr Ji Tae Kim from HKU’s Department of Mechanical Engineering, the new 3D label can encrypt more digital information than a traditional 2D label. The work has been published in Nano Letters.

Diphenylalanine (FF), a species of dipeptides, was chosen as a material for data encryption due to its unique optical properties, the team said.

First author of the paper, Dr Jihyuk Yang from HKU’s Department of Mechanical Engineering, explained: “FF has long attracted great attention to neuroscientists due to its association with Alzheimer's disease. Recently, FF is emerging as a new electronic and photonic device material due to its unique properties – such as piezoelectricity and optical birefringence – arising from crystalline nature.”

Dr Ji Tae Kim added that the team’s new 3D printing method combined with nature-driven molecular self-assembly can print multi-segmented 3D FF micro-pixels with programmed crystallinity for high-density data encryption.

“By utilising different responses of the amorphous and crystalline segments to polarised light, a tiny single 3D pixel can encrypt a multi-digit binary code consisting of ‘0’ and ‘1’. The information capacity can be increased to 211 with a single eleventh-segmented freestanding pixel on a tiny 4µm² area which is 1000 times smaller than a hair strand,” Dr Kim said.