The touch screen is not heat-sensitive, nor is it pressure. It uses electrical feedback harmless to the human body. So to trigger this, all you need is your finger ... or any other conductor.
Objects I've tested that work on touch screen:
A spoon (I think it's iron.)
A pencil wrapped in aluminum foil. This however requires you to make a flat or round end. A pointed end will not work.
A set of metal tweezers.
You get the point.
I am not responsible for any experiments and/or extended experiments you may try and therefore it is at your own risk that you try this and if you happen to get fried or your phone goes berserk, it's not my fault.