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Say I want to provide a device (completely batteryless of course, and detached from any human touch) the capability to immitate a touch on a capacitive screen (Galaxy S6 here). I know I just need some kind of a capacitor to touch the screen. I managed to register a touch by folding a piece of metal snack wrap (an inch square of it), put it on a piece of plastic, to escape my body's capacitiveness, and touch the screen with it. So, would I be able to do the same by connecting, let's say, an copper/aluminum foil to a capacitor, then touch the other side of that foil (or wires?) on the screen to register a touch?
I am asking about a capacitor, because I guess this would be the best/smallest solution to mimic our body's (connected to the finger) capcitiy. If I am totally wrong, and you have any other idea, welcome to suggest ;)
To make the question more clear: I want to mimic a finger (or multi touch) press, with the smallest/flattest possible (electrical?) device. I asked about a capacitor because it is small, and from my tiny knowledge in electronics, it "should do". So, this is not a general question like been asked before. I want to try and get to the specifics of how to mimic.