Sunbathers could soon tell when they have had enough sun - thanks to an early warning indicator.
The system, developed by Queen's University Belfast, is a strip of plastic containing 'smart' ink.
This turns colourless, from an initial blue colour, just before exposure to too much ultraviolet light from the sun.
The plastic strip, worn as a bracelet, changes colour at a speed that depends on the skin type of the wearer - and can be worn at the same time as sun lotion.
The technology was developed by Dr David Hazafy from Queen's University's School of Chemistry and Chemical Engineering.
He has been awarded a Royal Academy of Engineering's Enterprise fellowship.
His spin-out company, SunCatalyst Laboratories, uses photocatalysts - which work by harvesting energy from sunlight to drive useful chemical reactions, such as destroying bacteria or pollutants and changing the colour of dyes.
Dr Hazafy says it is a simple system.
