A Scottish school has turned to biometrics as part of a nationwide push to encourage children to eat healthier meals.

The cafeteria at Todholm Primary School in Paisley has gone cashless, and students are buying lunches by holding their hands over a palm-vein recognition unit produced by the Glasgow-based firm Yarg Biometrics. It's the first school to use the system. Inside is the same palm-vein scanner from Fujitsu that can now be found on thousands of bank cash machines across Japan.

The system relies on an infrared image of the palm of a user's hand. It reveals the pattern of veins present under the skin and from this an algorithm can confirm the identity of the user. It takes into account identifying features such as the number of veins, their position and the points at which they cross, and offers a higher level of security than competing technologies such as voice print, facial recognition, fingerprint recognition and iris scan, according to Fujitsu.

Scottish children in low-income families are entitled to receive free school meals, but until now the system has relied on a number of methods, such as different coloured tickets or separate queues, to differentiate those from children who pay for their own meal. As a result, it's relatively easy to work out which kids are from low-income households, and some students avoid receiving their free meal to escape the stigma that might go with it.

Going cashless will make this difference invisible. However, replacement systems involving swipe cards have their own problems with younger children, such as the cards being lost, said Alan Cunningham, managing director of Yarg Biometrics. Yarg worked with Fujitsu to develop the palm-vein readers that are used in the school.

Yarg discovered Fujitsu's palm-vein system a year ago and combined it with a keypad and other electronics to form the unit that sits on the counter-top. This is linked with a back office server that can verify the identity of each child and tie in with the food payment system.

At the school in Paisley there are four units linked to a back office server. Two of the units can be used by children to check their balance and the other two are installed at the cafeteria check-out. When a student places his or her hand in front of the sensor, the system returns the child's credit balance within about three seconds. A new version of the unit due shortly will cut this time in half.

It was installed about six weeks ago and the school is so far very happy with it, said Cunningham.

"The kids love it," he said. "It's the whole James Bond thing."