A condom that changes colour when it comes into contact with sexually transmitted infections has been invented by a group of school children.

The 'S.T.EYE' has a built-in indicator to detect infections such as chlamydia and syphilis, turning a different colour depending on the strain of bacteria present.

It is the brainchild Daanyaal Ali, 14, Muaz Nawaz, 13 and Chirag Shah, 14, pupils at Isaac Newton Academy in Ilford, Essex, who wanted to "make detecting harmful STIs safer than ever before" without the need for invasive tests.

You may think awkward post-coital silences are common enough as it is - but the group's ingenuity has been recognised with an award, the TeenTech gong for best health innovation.

Daanyall said: "We created the S.T.EYE as a new way for STI detection to help the future of the next generation.

"We wanted to make something that make detecting harmful STIs safer than ever before, so that people can take immediate action in the privacy of their own homes without the invasive procedures at the doctors.

"We've made sure we're able to give peace of mind to users and make sure people can be even more responsible than ever before."

The group get £1,000 and a trip to Buckingham Palace from the TeenTech awards, aimed at up-and-coming inventors.

Former Tomorrow's World presenter Maggie Philbin, founder and chief executive of TeenTech, said: "We encourage students to take their ideas out of the classroom by putting them face-to-face with industry professionals, helping to open their eyes to the real potential of their ideas."