Electrowetting principle

Electro-wetting principle: it refers to the phenomenon that the wettability of liquid droplets to their lower solid structures (generally strong hydrophobic materials) is changed by applying voltage between the upper and lower substrates, that is, the contact angle is changed, so that the liquid droplets are deformed and displaced. Wetting refers to the process in which one fluid on a solid surface is replaced by another.

When the liquid spreads on the solid surface, the solid-liquid contact surface tends to expand, that is, the adhesion of the liquid to the solid surface is greater than its cohesion, that is, wetting. The liquid cannot spread on the solid surface, and the contact surface tends to shrink into a sphere, that is, it does not wet. Non-wetting means that the adhesion of liquid to solid surface is less than its cohesion.

Electrowetting display technology is a method developed by using the natural force inherent in the interface between oil and water. This display technology was developed by Liquavista, a professional display manufacturer owned by Philips, and its research results were first published by Robert A. Hayes in the eighth issue of Nature in 2003. Philips has applied for a patent for this technology.

In this patent of Philips, a strong hydrophobic material is used as the functional structure of the display device. The surface of the display device will not be wetted by water without electricity, and the water phase and the oil phase are immiscible, forming a water-in-oil structure. When voltage is applied, the wettability of water in the hydrophobic layer changes from non-wetting to wetting, which pushes the oil phase to change shape.