Scientists have designed a grid of light responsive colloidal particles to function as pixels that could be used to create barcodes for cryptographic data storage.
Photochromic dyes are used in films to respond to light, for example in self-dimming sunglasses. These dyes have two isomers, one forms in visible light and is transparent, the other forms in UV light and absorbs light, darkening the sunglasses. If a photochromic dye is placed in a film with a fluorescent dye, and the wavelength of the fluorescence is matched to that absorbed by the photochromic dye, the photochromic dye can be used to switch the fluorescence off and on when exposed to UV or visible light.
Clemens Weiß and his colleagues at the Max-Planck Institute for Polymer Research in Germany, have devised a way to use this kind of light triggered dye switch to store data. Encapsulating the photochromic/fluorescent dye pair inside polymer colloids traps the molecules together prolonging the lifetime of the ‘on’ or ‘off’ state for several days. Assembling these functional colloids within a monolayer of larger colloids creates a grid of fluorescent ‘colloidal pixels’. Shining UV light on chosen areas of the grid turns the pixels’ fluorescence off creating dark areas on the grid whilst leaving others fluorescent.
Interested to know more? Read the full news article by Emily Skinner in Chemistry World here…
Read the article by K. Bley, N. Sinatra, N. Vogel, K. Landfester and C. K. Weiss in Nanoscale:
Switching light with light – advanced functional colloidal monolayers
K. Bley, N. Sinatra, N. Vogel, K. Landfester and C. K. Weiss
DOI: 10.1039/C3NR04897G, Paper