It appears there’s a new pen in town and since it has appeared under a couple of different brands I’d guess someone is licensing the technology to them
It’s basically a pen with an ink that loses its colour when heated, so when the cap of the pen is used to rub the paper, thus heating it by friction, the ink is “erased”.
It turns out that you can erase it with a hot air pen too.
There’s a kickstarter using these pens on a notebook that uses icons so that when you take a photo of the page with the matching app it stores the doodle accordingly. The interesting bit is that you erase the notepad by microwaving it. And by interesting I mean slightly scary, since the energy distribution and power output of different microwaves is so random that I’m sure some of these notepads might combust. That’s almost worth buying one for.
I suppose with the addition of a small paper label you could use these pens to detect when a component had overheated.
