When you wash your hands, how do you know if your hands are clean enough? Most of the time you don’t really know. A test would be to eat food using your bare hands and see if you get sick the next day – other than that, there’s really not much you can do. Well, some students from the Budapest University of Technology and Economics have come up with a way to determine if you’ve watched your hands properly. Called the Stery-Hand, it is basically a dark box with digital cameras, UV light and laptop to show you how your hands look under the camera. Users will have to wash their hands with a special UV-reflective disinfectant. After they are done washing their hands, they can see how much they’ve cleaned their hands by scanning them in the machine. Depending on the color intensity: red = not treated, blue = sufficient, green = well treated, you can tell how well they’ve cleaned their hands. Obviously the aim is to hit a green, and folks who don’t achieve it will have to wash their hands again.