Smartphone makers might soon not have much to brag about when it comes to the number of pixels they can fit on a pocket-sized screen. Researchers at the University of Cambridge have come up with a way to create pixels that are a million times smaller than those used on even Apple’s Retina displays. But extreme pixel density is somehow the least interesting part of this breakthrough.
The pixels are created by first coating microscopic gold particles – just a few billionths of a metre in size – with an electroactive polymer called polyaniline that can change its structure in the presence of an electrical field. That’s accomplished in a vat where the polymer and the gold particles are mixed, and the results are then simply sprayed onto a plastic film that’s been coated with a mirror finish. It sounds like a surprisingly simple process, and it turns out that’s one of the best features of this new technology: it’s relatively easy and cheap to manufacture.
Instead of exciting a chemical material to emit photons, light actually ends up getting trapped between those microscopic gold particles and the reflective backing they adhere to. But despite the diminutive size of the pixels, they actually end up producing a glow that appears much larger and brighter to the human eye even in direct sunlight. The colours of each pixel can also be tuned across the entire spectrum by applying a specific electric current which alters each gold particle’s polymer coating. Once changed, each pixel will retain its colour indefinitely, so a constant supply of power isn’t needed. So in addition to being affordable to manufacture and flexible, this new technology is also cheap to operate.
But how practical are these gold dust displays as a replacement for other technologies like LCDs and OLEDs? The researchers at the University of Cambridge have suggested potential applications like screens the size of large buildings, architecture that could change its appearance without the need for a paint job, or even garments that could actively camouflage the wearer the same way octopus or cuttlefish can hide in their environments – in other words, they’re envisioning applications that might be inappropriate for fragile, traditional displays.
But is the refresh rate fast enough to show moving video? Can the individual pixels be controlled with enough accuracy to produce recognisable images? The team is currently looking for partners to help further the development of their creation, and answers about just how far-reaching its applications could be may not be answered for a while.