This electric blanket has sensors that detect the room's ambient humidity and the humidity below the blanket. Presumably the difference between the two can be attributed to the perspiration of the person in the bed.
The blanket turns on when the humidity delta drops below the "low" threshold, and turns off when the humidity delta rises above the "high" threshold.
What makes this better than a blanket that you can dial a specific temperature for is its adaptive nature. If you climb into bed after spending a long winter day outside, the blanket will come up to its maximum temperature to warm you up quickly. After your body's core temperature rises (and this level of heat becomes uncomfortable) the blanket will sense this from your perspiration and reduce the temperature automatically.-- mwburden, Dec 29 2000 But if you turn it off completely, then it doesn't keep you warm on a cold winter night! (unless you pile on enough blankets that you feel smothered).
It also doesn't help if you want to get in bed as soon as you come in from the cold. (And my wife usually falls asleep within moments of getting under the electric blanket).
Finally, the main point was the adaptive nature of the whole thing. If you get up during the night to go to the bathroom (which is chilly at night!), the blanket will increase its temperature briefly when you come back to bed to compensate for your slight drop in body temperature.-- mwburden, Dec 29 2000 Adaptive nature indeed. I'm surprised this doesn't exist yet 'cause it's the small things (e.g. nightime bathroom use) that prevent current electric blankets from being the coolest invention next to the Sonicare toothbrush.-- iuvare, Dec 29 2000 random, halfbakery