Wearable UV Sunburn Detector

Cases of skin cancer are on the rise. Scientists are fighting back with a wearable sensor to tell us when we have had too much Sun exposure.

Who doesn’t love a bit of sunshine? Not only does it lift our moods, sun exposure also helps us to produce Vitamin D to strengthen our bones. But too much sun can cause serious, irreversible problems such as skin cancer. According to Cancer Research UK, skin cancer is the fifth most common cancer and every year approximately 15,400 new cases are reported, largely due to sun exposure.

Sunlight contains UV radiation we cannot see. It is made up of three components with different strengths and energies, creatively called A, B and C. UVA is responsible for skin ageing. UVB in small doses interacts with our skin to form vitamin D but too much UVB causes skin damage which can lead to cancer. High energy UVC is incredibly damaging to humans but luckily we are protected from it by the Earth’s atmosphere. 

We can use protection like suncream as a defence against UV, but we still don’t know when we have had too much fun in the sun. Now, wearable sun sensors in the form of wristbands have been developed by scientists at the Royal Melbourne Institute of Technology. “The sensor can allow people to be exposed to the maximum dose possible, without causing harm,” says Vipul Bansal, a researcher involved in the project that was published in Nature.

The Melbourne team made a series of six sensors tailored to the complete spectrum of skin types ranging from very fair to very dark. “The UV requirements and tolerance of these skin types are very very different,” says Vipul. “Very fair skin cannot tolerate a huge amount of UV.” The personalisation of the sensor gives an accurate representation of the time any individual with a particular skin tone can safely spend in the sun.

To make the sensor, all you need is a piece of paper and a fountain pen to apply the colourless ink containing the exciting chemistry. The "ink" comprises a dye molecule called polyoxometalate, which turns blue when exposed to the UV present in sunlight. The sensor becomes a darker and darker blue until the safe 100% exposure limit is reached. As the colour change is permanent, the blue colour does not fade in the shade or overnight. Instead, the sensor is designed to be single use to show your sun allowance for one day.

But what if you use suncream? Well, you can apply it to the sensor as well as yourself to show accurately the safe extra amount of time you can spend in the sun thanks to the extra protection conferred by the suncream. Similarly, the sensor is waterproof, so when you go swimming at the beach and your suncream rubs off, this will be reflected by the sensor and alert you to re-apply.

For those keen to join the legions of sensible sun worshippers, the Melbourne team are aiming to bring their sensor technology to the market by early 2020. Lucky for us smart sunbathers, the sensor raw material cost is low, so sun safety will only set you back 50 Pence, or about 1 Australia Dollar.

So when you hit the beach with your sun safety sensor, “sun’s out, buns out” will be replaced with “sun’s out, sensors on”...