Irritating tattoos

Cranfield University in the UK wants to make patch tests for allergens more attractive. Usually, an array of samples, such as cosmetics, or shampoos are held in place on the skin by a variety of unsightly sticking plasters. But people don’t like wearing them. In patent application WO 03/105694, Cranfield suggests building several suspect ingredients into different inert dyes and applying them to the skin as a temporary stick-on tattoo. When the tattoo is stripped off after a few days, the shape and position of any inflammation can be checked against a map and key of the ingredients in the…