I've had a very private love affair with holograms for as long as I can remember, pulling my parent's Visa card out and sitting mesmerized for hours, gently swaying from side to side. So it goes without saying that I'd think the technology Smart Holograms has developed is kickass, even if I have mostly no idea how it works.
The image is stored in a thin polymer film that is chemically sensitised to react with a specific substance in, for example, a bioassay or a sample of body fluid. During the test, the target substance reacts with the polymer leading to an alteration in the image displayed by the hologram. The test result is a change in the optical: brightness, image, wavelength or position.
Prototypical applications include a contact lens that can monitor glucose levels, a badge that can test how inebriated you are, and a sour milk indicator, among others. If there's a cooler way to discover that I have more STDs or that the milk is off than a holographic dragon giving me a wink, I don't know it.