Magnetic Displays

The current demand for low-cost electronic materials and more integrated consumer products has created a strong need for ultra low cost electronic displays with high optical sensitivities.

Magnetically controlled particle orientation enables tunable reflectivity

The incorporation of highly reflecting aluminum flakes in a superparamagnetic fluid resulted in an extremely sensitive system with controllable optical properties. The application of a local external magnetic field favors the controlled orientation of aluminum flakes. This results in the tuning of optical features such as reflectivity. The strong response of the magnetic fluid to a magnetic field enables the use of very low solids concentrations without affecting the orientation precision of the reflecting agents. The highly field sensitive tuning of reflectivity allows the development of ordered devices such as windows or displays, in which the optical features are visible, even under small observation angles in contrast to current LCD displays.Furthermore, based on this system materials with anisotropic properties can be build up, for example polymers with anisotropic electric and thermal conductivity. [research projects available]

Switchable reflectivity. Magnetic fluid film (0.2mm) between two capton foils (left) reflecting due to a magnetic field parallel to the plane and (right) transparent, due to a perpendicular field.

Short movie: magnetic display

Further reading:

• S.B. Bubenhofer, E.K. Athanassiou, R.N. Grass, F.M. Koehler, M. Rossier, W.J. Stark, Magnetic switching of optical reflectivity in nanomagnet/micromirror suspensions: colloid displays as a potential alternative to liquid crystal displays, Nanotechnology, 20, 485302 (2009).
  DOI: 10.1088/0957-4484/20/48/485302