By Geoff Adams-Spink
Age & disability correspondent, BBC News website
Ruth Amos set up her company when she was only 16
A young woman from Sheffield has turned a GCSE coursework project into an award-winning stair-climbing device for older and disabled people.
Ruth Amos has launched her StairSteady handrail at Naidex 2008 - the annual disability exhibition in Birmingham.
She told BBC News that she was inspired to create the device for the father of one of her teachers who had had a stroke.
She won an award for her idea and has now set up a company to sell it.
The StairSteady is a horizontal rail at 90 degrees to the wall or banister that people can hold on to as they go up or down stairs.
A friction device inside the handrail enables the user to move it up or down but it locks when weight is applied in order to give added support.
Ms Amos says her invention will enable people who have difficulty with stairs to remain active - something that she says is not the case when a stair lift is fitted.
"Our product will fit any width of stairs and it's also low-cost," she said.
The device will be on sale for £329.00 plus the cost of fitting.
"You have to have it fitted because of the safety requirements and the weight that it holds," Ms Amos explained.
The StairSteady was designed as part of her GCSE coursework two years ago.
"It was initially for my teacher's father who'd had a stroke - we decided that we wanted to design something to help him because he'd been told to keep active but he wasn't able to."
The invention was then entered for the Young Engineer for Britain competition and won first prize.
Since then - encouraged by her family - Ms Amos set up a company to market her product which had its launch at Naidex 2008 at the NEC in Birmingham.
She says that she would like to go to university to study engineering but that she has spent most of the money saved up for her studies on hiring a stand at Naidex.
"I'm taking a couple of years out to run the product first."
The StairSteady is now being assessed for potential outdoor use as well.
The bar pivots vertically when not in use and the only setting in which it cannot be used is spiral staircases.
Asked about possible future projects, Ms Amos says her abiding philosophy is to keep things simple.
"I think there are always ways to improve things and they're not always the most complicated ways."
Naidex 2008 is at the National Exhibition Centre in Birmingham from April 29 - May 1.