Ink-based sensors cut sunburn risk

Skin cancer caused by unprotected exposure to ultraviolet radiation is highly preventable, says the United States Environmental Protection Agency. To give people a better chance at being safe in the sun, researchers from Australia’s Royal Melbourne Institute of Technology (RMIT) have developed wearable sensors that provide an accurate and simple measure of personal UV exposure levels throughout the day.

Each year, more new cases of skin cancer are diagnosed in the US than new cases of breast, prostate, lung, and colon cancer combined, the EPA says. One in five Americans will develop skin cancer; one dies from skin cancer every hour.

In Australia, where the incidence of skin cancer is one of the highest in the world – two to three times that of Canada, the US or Britain – the numbers are even more stark, according to the national Cancer Council.

About two in three Australians will be diagnosed with skin cancer by the time they are 70, it says, with more than 750,000 treated for one or more non-melanoma skin cancers each year. In 2015, 2162 Australians died from it.

The cancer, the council says, occurs when skin cells are damaged – commonly by overexposure to UV radiation from the sun.{%recommended 6953%}

The researchers, led by RMIT’s Vipul Bansal, explain their work in the journal Nature Communications. Their primary achievement is the invention of a UV exposure warning signal that can be read by the naked eye.

Bansal says the new UV sensor technology allows the production of “personalised sensors that can be matched to the specific needs of a particular individual”.

The scientists developed an invisible ink that has a chemical reaction to sunlight. This can be used to create a low-cost, paper-based UV sensor that gives an easily seen measurement of a person’s exposure to radiation.

They have developed six versions to accommodate people with different skin types, from very fair to dark brown.

“We can print our ink on any paper-like surface to produce cheap, wearable sensors in the form of wristbands, headbands or stickers, for example,” Bansal says.

The paper’s illustrative material shows a sensor strip calibrated into smiley-face icons, from happy to sad.

The paper explains that ultraviolet radiation (UVR) comprises three types: UVA, UVB, and UVC.

The longwave UVA penetrates deep into the skin and its cumulative exposure over lengthy periods results in skin ageing and wrinkling.

UVB exposure can damage DNA, and short bursts of high UVB doses cause sunburn, increasing the likelihood of developing skin cancer and cataracts.

The shortwave UVC has the highest energy and can cause deadly damage to all lifeforms.

Fortunately, the paper says, the Earth’s atmosphere filters out most of the solar UVB and all UVC. Therefore, the solar UVR that reaches the planet’s surface is a combination of UVA and UVB.

“Further, due to the depletion of the stratospheric ozone layer, our natural protective filter is progressively declining,” the paper says.

“This is leading to higher levels of UVR reaching the earth’s surface, particularly in regions such as Australia, where the ozone layer is significantly depleted.”

Bansal says his team’s “low-cost and child-friendly” UV sensors could replace expensive, cumbersome mechanical varieties.

They could also be used as educational materials to increase awareness of sun safety, he says

The researchers say their discovery also has applications beyond the health sector, because of the damage UV rays can inflict on many industrial and consumer products.