By Cameron Chai
University of California, Riverside scientists have designed nanoscale-sized apparatus comprising iron oxide particles that react to an outside magnetic field, enhancing visual data being displayed.
The research paper was published in the March 14 issue of Angewandte Chemie. The back cover of an upcoming print issue will also feature the paper.
Yadong Yin's lab has applied a layer of silica (silicon dioxide) to iron oxide particles. When they unite in solutions like linearly connected spheres, they form minute rods or nanorods that retain their peapod shape.
The magnetic field applied to the nanorods ensure that they array parallel to each another like flashlights turned one way, and reveal a bright color. The nanorods are photonic shapes that diffract visible light. This project will help fabricate photonic shapes that will respond to magnets with reduced sizes to achieve color with better resolutions. The technology can be applied in pattern formation, posters, images, power efficient color displays, and traffic signals using different colors. They can also be used in bio- and chemical sensors, biomedical marking and imaging. Color displays that are not easily visible in sunlight, like laptop screens, will be visible on devices using nanorod technology.
Yin and his students, Yongxing Hu and Le He, first covered the magnetic iron oxide molecules with a thin coating of silica. Then a magnetic field was applied to form them into chains. The chains were then covered with another coating of silica to create a shell around the chain to stabilize it. The space between the interparticles can be adjusted when it is exposed to the magnetic field. This does not impact the color, which can be monitored by the duration of the exposure to the magnetic field. The magnetic repulsive energy perpendicular to the direction of the magnetic field ensures that the particles remain equi-distant from one another, allowing them to display only one color.