This is just a fun property of the exhaled vapour I found while I was vaping and reading a book on my e-reader. I use a Kobo glo reader and it comes with IR touch sensor rather than a capacitive one. What I found was the screen responds to the warmth of the exhaled vapour!
Now you can read while vaping and turn pages sans hands with just a well aimed puff of vape! Pretty cool huh?