A sensor worn on the thumbnail could prevent skin cancer by alerting wearers when they are getting too much sun exposure. The battery-free UV Sense device detects radiation from the sun and changes colour to show how high levels are.
By measuring how long a wearer has been outside, the device, which is less than 2mm thick and 9mm in diameter, encourages users to reapply sun cream when scanned by a user's smartphone. UV Sense, which launched in the US last week, is due to be available in the UK in 2019. Its price is unclear.
Melanoma, which is the most serious form of skin cancer and often spreads, affects more than 15,000 new people every year in the UK. Its main cause is overexposure to UV light.
