I am doing project in which I want to perform read and write operation by using a capacitive touchscreen. What I know is I can trigger capacitive touch screen by:

  1. By using electromagnet as I heard that some of stylus works by using magnet at its point so I think electromagnet should work.
  2. By using capacitor: If I connect a capacitor's one end to vcc and other to a conductor plate then I think it will mimic the property of human finger and trigger touchscreen.

I want to use these system so I not need to make any physical changes. If I want screen to trigger then I can just charge capacitor or electromagnet. I want to know that whether my theory is correct or not and if there is any suggestion for that then let me know.


Capacitive touch screens work by altering the AC electric field on a fine grid in the phone screen that's detected as a change in capacitance at that node.

You should be able to alter the capacitance by touching the screen with a grounded electrical conductor. A quick trial with my phone shows this works.

Confirmed on EEVblog by this post."I work with capacitive touchscreens daily. When we need to control when a finger is applied to the screen, we use copper tape. The tape has a conductive adhesive that keeps it on the screen. Then, a short wire to a NO relay. When the relay is activated, it connects the copper tape to ground. This increases the response to the sensor and usually appears as a finger. I've also been looking at using a series capacitor to isolate the connecting wire from the proxy finger. "


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