The only time that I remember dreaming with my phone, I was trying to turn it off, while its real life counterpart rung furiously.
I've dreamt some times with my desktop though. Such as:
- my cat pulling out the mouse from my computer, sitting in its place on the mousepad, and then meowing loudly (she does this a lot when she's play-hunting)
- throwing potatoes on the screen, so I could get some French fries in return
- keyboard gardening: the keys were subbed with small pots full of dirt, some with small versions of plants. A lot of them were pepper plants and I was trying to cross-breed them.
If you're talking about strips that look like this:
I believe that most brands use Benedict's reagent: copper sulphate, sodium citrate, sodium carbonate. It interacts with reducing sugars (like glucose) and the colour goes from blue to light green to green to brown-green to brown-red, depending on concentration.