Scientists demonstrate magnets that can control the colour of a liquid
Chicago (IL) - An iron oxide water-based solution has been discovered which changes color under varying magnetic field strengths. The solution works at extremely small scales and would be suitable for displays as well as new applications.
To produce various colors a magnetic field must be created. A non-existent field yields the traditional brownish rust color. As the field gets stronger the colors move from brownish to red to orange to green to cyan and finally to blue. There are varying degrees of color in between. The colors hit the red, green and blue bands used in traditional color displays (like LCDs).
The big advantage here is that the system uses light reflected back to the user by the iron oxide solution. The more light there is the brighter the image appears. This makes the application suitable for outdoor displays as well as indoor.
Researchers have been working on technologies which would allow bright, low-power displays on flexible mediums for several years. This new solution can be deposited as a colloidal solution, added to any flexible substrate capable of also holding the required RGB pixel circuitry. Since the iron oxide solution does not require a backlight for it to show color, it does not have to be transparent. This makes the possible range of substrate materials much broader. Another possible proposed solution is the idea of erasable/rewritable paper.
The iron oxide nanoparticles used in the colloidal solution are superparamagnetic. This means they turn magnetic only in the presence of an external magnetic field. This trait would enable the solution to work for displays of various kinds, only requiring power when a pixel is displayed. This makes it similar to OLED technology, except that this solution reflects light when powered rather than generating it.