Electrowetting Could be a Disruptive Technology for End Users
While the amount of information that we digitally process ever increases many people still prefer to read from paper rather than electronic displays even though the cost is greater with printing.
Many companies are developing electronic paper, which combine the desirable viewing characteristics of conventional printed paper with the ability to manipulate the displayed information electronically. Electronic paper based on the electrophoretic motion of particles inside small capsules has been demonstrated and commercialized; but the response speed of such a system is rather slow, limited by the velocity of the particles.
Philips Research in Eindhoven, the Netherlands have demonstrated that electrowetting is an attractive technology for the rapid manipulation of liquids on a micrometer scale and have shown that electrowetting can also be used to form the basis of a reflective display that is significantly faster than electrophoretic displays, so that video content can be displayed, something not possible with the more publicised electrophoretic displays to any practicable extent. A disadvantage is that electrowetted displays are not bistable ie they still need power even when the display image is not changing, whereas electrophoretic displays do not. However, IDTechEx believes that this is only a disadvantage when images are frozen for very long periods, notably with posters, billboards and signage or certain types of electronic label.
Electrowetting makes use of the natural forces intrinsic to an oil and water interface and methods developed for the manipulation of these forces. Separate oil and water phases are formed using a highly hydrophobic material which causes the water to be repelled from the surface, the oil film acting as an intermediate.
The wetting properties of the hydrophobic surface can be modified by the application of an electrical voltage (hence the name Electrowetting) and the surface becomes increasingly hydrophilic (wettable).
As the previously unwettable (hydrophobic) surface becomes increasingly attractive to the water, the oil is forced to adopt an alternative form. This manipulation of interfacial properties is what forms the basis of Electrowetting applications.