Halion has developed a novel liquid ink material which can rapidly change between two colours. The change is actuated with an electric field applied across the ink. Very little power is needed to change the colour, and even less to maintain it.
Charged particles within the ink carry custom colour changing molecules. When the particles are in contact, the ink changes colour. When an electric field is applied, the particles are pulled out of contact in just a few milliseconds, reversing the colour change.
In a typical device our ink is applied between two conductive substrates. The substrates may be simple conductive films, or patterned TFT substrates. The ink only changes colour where an electric field is present.