Three schoolboys behind a colour-changing, STI-detecting condom say they've been contacted by a contraceptive company about their idea.

Daanyaal Ali, Chirag Shah, both 14, and Muaz Nawaz, 13, won a TeenTech award this week for their idea, called S.T.Eye.

They want to create a condom that changes colour when it detects an STI.

Muaz told Newsbeat: "We wanted to make a product that will make life simpler, easier, better."

Their idea - which is still at concept stage - involves a condom covered with antibodies that would react with the proteins in bacteria, or antigens, found in STIs.

Daanyaal explained: "Once the [bodily] fluids come into contact with the latex, if the person does have some sort of STI, it will cause a reaction through antibodies and antigens hanging on to each other, which triggers an antibody reaction causing a colour change.

"We took inspiration from an HIV testing method [called Elisa] which utilises colour-changing."

The students said the colour change would work on both sides of the condom, with different colours for different STIs - green for chlamydia, purple for genital warts, blue for syphilis and yellow for herpes.

Chirag said: "It prevents [people] from getting embarrassed going to clinics, and [lets them] find out in the privacy of their own home."

The idea for S.T.Eye came about in a Dragons' Den style competition at their school in Ilford, London.

Muaz said: "We were searching the internet and we came across a Reddit post called 20 Things That Should Be Invented, and it said a colour-changing condom. We decided to add the twist of reacting with an STI.

"We never thought we would pitch it, we thought we would get in trouble. Even though it's a serious topic, [we were worried] some people would think we were taking it as a joke."

The boys said they wanted to help because STIs affect loads of people.

Daanyaal said: "We noticed how big the condom market was. We saw it was huge because in England there were 450,000 diagnoses of STIs in 2013 alone.

"We got help from our science teacher and he told us about antibodies and antigens and how that would work."

The boys said they still have to test the science and feasibility of their idea.

They want to work with a university on the science and say they've already been contacted by a condom company which is interested in working with them on developing the concept further.

Chirag, Daanyaal and Muaz won the healthcare category at the TeenTech awards, which challenge students aged 11 to 16 to use technology to solve real-world problems.

They won £1,000 for their school and are going to Buckingham Palace in October to meet the Duke of York.

Could colour-changing condoms actually work?

We spoke to Dr Mark Lawton, who's a consultant in sexual health and HIV, and from the British Association for Sexual Health and HIV (BASHH).

He told us: "The technology for colour change in the presence of an antigen is certainly something that does happen - the home test for HIV relies on a colour change detecting antibodies for HIV.

"It does normally require some additional chemicals in that process and [with a condom] you'd obviously need to make sure that those chemicals weren't going to be harmful or toxic or in any way cause irritation.

"It's possible, [but] I'm not sure we have what we need at the moment."

Dr Lawton identified some possible problems: "To play devil's advocate, would it dissuade people from using condoms if they were worried about being found out?

"Or if they were worried that the person they were going to have sex with didn't want to have sex with them if they found something?"

But overall, he commended the teenagers for being aware of STIs and being driven to reduce the problem.

Head to the BBC Advice pages for more information on sex and relationships.

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