I am trying to create a circuit that will be able to detect a touch (with fingertip) on a metal/aluminium surface that it is connected to. Currently I have this circuit (I am sorry for bad drawing...):![enter image description here](https://i.stack.imgur.com/tQx8c.png)

My assumptions are probably wrong, but this is what I was thinking of. Due to human skin having some capacitance, when one would touch the plate, there would be some current flow due to change in capacitance. High pass RC filter would get rid off DC offset and the signal would get amplified by LM358. This would then trigger 555 timer in monostable mode.

Any help is greately appreciated!