Rear-end rainbows

Having great-great-great grandchildren in possible prospect, I include ads for baby-gear in my reading. Here's a half-baked idea generated while studying a diaper ad - disposable d's that react by changing colour when urine or feces containing illness indicators contact them. There would be single-illness diapers on free-issue for early warning during epidemics, and hitech ones for sale, reactive to more than one illness by changing to differing colours. Microcapsule technology might be the way to do this. But I dunno. The Halfbakery has made me able to shrug off my former compulsion to research my doughy ditherings. Thanks Jutta!