John Roberts says he is happy to be a "guinea pig" if he can help others.
"There are people a lot worse off than me who have lost limbs," says the grandfather from Gloucester, who recently had part of his leg amputated.
The 70-year-old is part of a research project that could transform the lives of the thousands of people in England alone who have had a lower limb removed.
"No more pain," he says of life after surgery.
"I'm walking now, gardening, doing everything more than I was doing all those years ago."
In a laboratory at Bath University, he pulls off his prosthetic, unpeeling three layers of socks and the silicone liner he wears to keep the prosthetic from rubbing.
John was born prematurely with one leg longer than the other. Boots, callipers and an operation all failed to relieve his pain and he recently took the last resort of an amputation, which has improved his quality of life.
Like all people in his position - around 45,000 in England - he faces a long recovery process, as the stump of his leg changes size and shape after the operation.
The pain and discomfort can lead to some patients abandoning their prosthetic limb altogether and relying on a wheelchair.
Scientists and engineers at Bath are developing made-to-measure synthetic liners to aid the healing process, which can be manufactured and fitted in less than a day.
It's going to make "a massive difference", says John. "I'll be happier. As far as I'm concerned, it'll make life easier."
In a high-tech laboratory at Bath University, John has his residual limb digitally scanned in 3D.
Engineers at Bath then convert the measurements into code and a machine makes a synthetic liner based on his individual contours that fits like a "glove".
How it works
• Researchers use a 3D scanner to get a detailed image of the residual limb and to design a custom-fit liner
• The liner is cryogenically manufactured from a flexible neoprene-like material (similar to that used in wetsuits)
• The liner is tested using sensors in the socket to check there are no pressure points where the liner could cause skin damage
• The patient's gait and loading of joints are checked using a motion-capture system.
It's evidence, says Dr Vimal Dhokia, of how engineering can solve the problems of everyday life.
With personalised products you're meeting the precise needs of the individual patient, creating a product that fits better and can help them heal better, the reader in design engineering says.
"They can move around better, they don't have the issues you have with current products which require changing continuously or, in John's case, requires a silicone liner and a number of socks."
We move from engineering to another laboratory where Dr Elena Seminati puts sensors on John's limbs. This enables her to analyse his gait on a computer and to check the prosthetic "slipper" fits him perfectly, with no pressure points.
"This liner will help John to have a better life, a normal life," she says.
For John, one big advantage is the speed at which he would be able to put his prosthetic leg on in an emergency.
He is particularly worried about getting out quickly if there were a fire in the night.
Now he is looking forward to getting on with his life. And he says if this project can be used to benefit others down the line, he will be happy.
"If I've got to be a guinea pig, I'll be a guinea pig, I don't mind," he says. "Because I always look at life - somebody's worse off than me."
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