Aluminum Home Sticker

My dad was recently inn Japan and found these Aluminum Home Seal stickers (Sailor Moon because yeah i'm a nerd) and they SAY they're meant for touch id as well. I just want to know HOW this is possible?

While they're super cute, i dont really want to mess up the button, but I'm curious if anyone had any idea how these would work? My 6S is on the way still.