The Suncayr pen's ink changes colour when exposed to UV light, letting you know when your sunscreen's no longer protecting you adequately.

Suncayr offers an additional layer of protection for lovers of the great outdoors. Draw it on before you apply your regular sunscreen, and when your sunscreen is too worn to protect you, it turns purple. 

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The Canadian company has been selected by the Kairos Society as one of its K50, representing "the next generation of entrepreneurs making breakthroughs in the areas of biotech, education, agriculture, mobile, cleantech and healthcare."