Personally I find this device a little worrying, I'm quite lucky because I can detect a hypo at around the 3.9mmol mark and I have had the "cold sweat" but not until well into the 2's which personaly is cant stand up territory for me!!!
Ive been on top of a mountain in Bulgaria on my own Snowboarding, and ive had a hypo, recognised it, sat down, munched a few glucose tablets and sorted it, I dread to think what would have happened if id have waited until a device like this kicked in !!!
Like Sarah said, you should try to recognise your hypos yourself and not rely on something like this which to me seems to be a basic moisture sensor, something that could be knocked up by a school kid in a science class !!!