News from Nanotechjapan


Full Colour Pixels Created by Nano Structured Aluminium -Ink Free Colour Printing with Controllable Hue, Brightness and Saturation-

 On April 26, 2017, Institute of Physical and Chemical Research (RIKEN) announced that a research team from Metamaterials Laboratory of the institute has developed a new full colour printing technique by using plasmonic pixels of metamaterial with nanostructured Al thin films.  Details were published in Scientific Reports with Takuo Tanaka as principal author *.

 Conventional colour printing relies on several colour inks, each of which absorbs different wavelength of light. Colour of inks, however, fades-out with time or strong light irradiation. Nano structured metamaterials provide permanent colour, whose wavelength corresponds to excitation energy of plasmon in a nano pixcel. To apply such structures in practical use, individual colours with distinct reflective peaks and tunability across the whole visible wavelength region are highly demanded.

 The research team has developed metamaterial with square-shape sub-micrometer plasmonic pixels, whose colour is determined by a length of the square side (260~420 nm) and a gap length between two adjacent squares (100~180 nm). Colour pixels are fabricated by electron-beam lithography and vacuum deposition of Al with 45 nm thickness onto the square-shape photoresist of 150 nm thick on a Si substrate. The newly developed plasmonic colours have advantages such as fade-free, very thin (<200 nm), light in weight (1/500 compared to conventional ink).

* Renilkumar Mudachathi and Takuo Tanaka, "Up Scalable Full Colour Plasmonic Pixels with Controllable Hue, Brightness and Saturation", Scientific Reports, Vol. 7, Article number: 1199 (2017), doi: 10.1038/s41598-017-01266-6; Published online: 26 April 2017