Simple paper sensor tells you when to get out of the sun

sun tan
CC BY 2.0 Eidoloon

Summer is upon us -- long days spent outdoors, at the pool, the park and the beach, and, obviously, in the sun. We already know that sunburns lead to an increased risk of developing skin cancer and watching our sun exposure is key to keeping our skin and ourselves healthy, but even with the most diligent use of sunscreen, burns can still happen if you're outside long enough.

A group of Australian researchers, lead by J. Justin Gooding, set out to develop a sensor that would tell you when to head indoors or cover up before a sunburn happens. The resulting paper-based sensor helps people monitor their sun exposure and can account for different skin tones and sunscreen levels, both of which affect the amount of time a person can remain in the sun without getting burned.

Sun monitoring tech is nothing new. We've covered smartphone-based monitors and Lloyd wrote about a very chic UV-measuring bracelet he saw a couple years ago at CES. These ideas are great, but the problem is that they require expensive gadgets, which isn't exactly the first thing I want to pack for a day at the city pool and it also excludes people who can't afford them.

Gooding and his colleagues' paper sensor on the other hand would be an extremely cheap and disposable alternative. Just stick it on your bathing suit or clothing while you're outdoors and you can toss it at the end of the day. Before you start worrying about "disposable" e-waste, there are no electronics in this sensor, just titanium dioxide and food dye, which are safe and benign materials.

The group made the sensor by printing the titanium dioxide and food dye on the paper using an inkjet printer. When a certain amount of UV radiation hits the sensor, the titanium dioxide causes the food dye to change color. When that happens, that indicates that the person either needs to reapply sunscreen or get out of the sun completely. Of course different skin tones and SPF levels would extend that time, the researchers added UV neutral density filters that can speed up or slow down the color change in the sensor based on those factors.

While we should all use common sense and follow expert advice when it comes to sun exposure -- wear sunscreen all over daily, cover up with hats and clothing, stay in the shade, etc. -- the fact is most of us don't adhere to these very well. Even if you're strict about sunscreen use, experts say it's not enough if you're going to be outdoors all day. Having a device or cheap paper sensor as another layer of protection to make sure we really do stay sun safe could only help.

Simple paper sensor tells you when to get out of the sun
The sensor could help people avoid sunburns from too much summer sun.

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