Researchers at Missouri University of Science and Technology are giving new meaning to the term “read the fine print” with their demonstration of a color printing process using nanomaterials.
In this case, the print features are very fine – visible only with the aid of a high-powered electron microscope.
The researchers describe their “no-ink” printing method in the latest issue of the Nature Publishing Group journal Scientific Reports and illustrate their technique by reproducing the Missouri S&T athletic logo on a nanometer-scale surface. A nanometer is one billionth of a meter, and some nanomaterials are only a few atoms in size.
The method described in the Scientific Reports article “Structural color printing based on plasmonic metasurfaces of perfect light absorption” involves the use of thin sandwiches of nanometer-scale metal-dielectric materials known as metamaterials that interact with light in ways not seen in nature. Experimenting with the interplay of white light on sandwich-like structures, or plasmonic interfaces, the researchers developed what they call “a simple but efficient structural color printing platform” at the nanometer-scale level. They believe the process holds promise for future applications, including nanoscale visual arts, security marking and information storage.
The researchers’ printing surface consists of a sandwich-like structure made up of two thin films of silver separated by a “spacer” film of silica. The top layer of silver film is 25 nanometers thick and is punctured with tiny holes created by a microfabrication process known as focused ion beam milling. The bottom layer of silver is four times thicker than the top layer but still minuscule at 100 nanometers. Between the top and bottom films lies a 45-nanometer silica dielectric spacer.