Labelled with liquid crystal

Price labels on the shelves of all branches of a supermarket could change automatically at the touch of a button in a central office, thanks to new electronic labels.

The bi-stable liquid-crystal devices were developed by ZBD Displays, a QinetiQ spin-out company, in collaboration with Sheffield Hallam University (SHU). The researchers anticipate the new technology could also be used in low-power mobile phone displays and smart cards.

Professor Chris Care from the University’s Materials and Engineering Research Institute (MERI) said, “It takes supermarket staff a long time and up to three people to change prices overnight. The new device will change all prices instantaneously and it can be coordinated nationally or even worldwide.”

The labels use very high definition liquid crystal displays with an innovative grating inside. One surface is scored with 1-micron ridges using CD-making technology.

Cliff Jones from ZBD said, “”We use an embossing technique. A nickel master is stamped into the film. Equivalent energies competing across two alignments create a fully black and white state that won’t change until a further charge is applied.”

Updates are made from a localised radio frequency system. A single aerial can update 10,000 labels.

“It uses very little power as current only needs to be applied to change the label. It stays the same until another change needs to be made. It is very well suited for the application, but wouldn’t work so well in a continually refreshing environment’” said Care.

Jones added, “LCD displays normally refresh 30 times a second, which would mean the batteries would need to be replaced every 30 days. Our system means they could last over five years.”

ZBD Displays and SHU scientists were granted £1 million by the Department of Trade and Industry for the joint project.

Sheffield developed a computational model for the LCD device. “LCD is complex and expensive. Our model allows us to manipulate the 15-20 different parameters which affect its behaviour,” said Care. “We’re now refining the model which will allow us to optimise the device.”

The labels are entirely food-safe, and as they do not have to be touched or have pens used on them, they are suitable for use right next to food, as in deli counters. Branches of John Lewis and Tesco are currently trialling prototypes of the device.