Remember when mood rings were cool? That was a trick question, they've never not been. As a matter of fact, I'm wearing like forty of them even as I type this. Two on my penis! He's super sad right now.
This is one of those things that is so obvious that you want to smack your head against the wall for not thinking of it first. Researchers in Munich, Germany have invented an indicator dye that changes color when bruises become infected.
The researchers at the Fraunhofer Research Institution for Modular Solid State Technologies EMFT say that the the dye works by measuring pH values. Regular human skin and healed wounds have a pH value around 5 -- if the pH value goes up to 6.5 or 8.5, then the dye will change color from clear to purple. When it changes to purple is when you should start panicking because you'll likely have an infection.
Don't get me wrong, they sound like a great idea and all, I just wonder how much more expensive they're gonna be. Because if a doctor puts it on you KNOW your insurance is gonna be billed like sixty-thousand dollars. Thankfully, I happen to know a much simpler way to determine if a wound is infected: smell it. Does it smell like maggots? Goop some Neosporin on that bitch STAT!