Doctors are set to unveil the world's first sticking plaster that can cure cancer.
The high-tech device contains a small light that combines with a chemical cream to kill skin cancer cells.
The Ambulight plaster has already been used on 50 patients with a success rate of up to 90%. It is less painful than surgery and leaves no scar.
Muriel Lowe, who had two treatments a week apart, described the result as "fantastic".
She said: "I have a skin condition that means normal surgery would scar me.
"The doctor told me that cosmetically this would be much better. The treatment is called photodynamic therapy."
A cream containing a harmless chemical is rubbed into the skin where it is absorbed by skin cancer cells, but not healthy tissue.
Three hours later the LED in the plaster automatically switches on for a pre-programmed duration, converting the chemical into a lethal drug.
It kills cancer but minimizes collateral damage to healthy cells.
Professor James Ferguson, the consultant dermatologist at Ninewells Hospital in Dundee, invented the device and has been using it to treat non-melanoma skin cancer.
"We get an 80-90% complete cure," he said.
"What we are hoping to do is optimize it further, by using new ways of delivering the light... pulsing for example. So there is room for improvement."
Professor Ferguson said the device is so simple to use that it could be applied in a GP's surgery, freeing up hospital space.
The Ambulight is being officially launched at the European Society for Photodynamic Therapy in Monaco.