The EcoHelmet is designed for people who use bike-sharing schemes and might not always have a helmet with them.

Designer Shiffer is delighted with the win but admits that a paper helmet may be a "tough sell".

She describes herself as an "ardent but slow" cyclist and came up with the idea when she was using bike-sharing schemes around the world.

"When I was exploring new cities I had no access to a helmet and I didn't want to spend $30 buying one," she told the BBC.

She decided to design one, made of cheap, recyclable materials that would cost less than $5.

The helmet uses a honeycomb structure to protect the head which, according to Ms Shiffer, is "incredibly good at absorbing impact".

The design was tested at Imperial College in London.

They have a test rig for helmets and the professor in charge of the lab let me test out a lot of materials. It turns out it was a lot of fun. There is a frame with an anvil on the bottom and an accelerometer to measure speed and impact," explained Ms Shiffer.

She admitted that it may be a "tough sell" convincing people that it works.

Since 2002, the James Dyson Award has been open to university or recent design graduates across the world.

Ms Shiffer will receive £30,000 to further develop the helmet. Describing it as "the holy grail" of design awards, she said that she was "astonished" to win it.

She hopes to pilot the new helmet in New York in the spring, possibly offering it free to bike-share users at first.

The helmet is designed for a limited number of uses and will deteriorate and weaken over time, especially if carried around at the bottom of a bag. The final design is likely to have a visible stripe that will wear off when it is time to throw it away or a clip that ceases to work after a certain amount of time.

The UK's Royal Society for the Prevention of Accidents said it was unable to comment as it did not know enough about the product and whether it would meet safety standards.

212