You've heard of mood rings? Philips, the electronic company, has filed a patent for a mood pen which can record your emotional state as you write. The sensors in the pen's shaft monitors your heart rate, blood pressure, skin temperature and pressure. The pen is able to change inks and the shape of the writing tip. The in-built sensor determines your mood based on the physiological readings detected and the pen will adjust the inks and tip shapes as your write. The words you write when you are sad will therefore look different from those written when you are happy.
"Signatures are currently always the same, yet some documents will be signed with enthusiasm, others possibly with hesitation," Philips says. "Having a recording of this could be useful for historical reasons."
If you don't want anyone to see how you are feeling, there could be a button to switch off the pen's mood function. Or you could switch to a normal pen!