for a science-project I need to create 4-5 capacitive touch buttons through thick glass or macrolon. I think we talk about 15cm atleast, if not 20. I wonder if a big coil or big sheet of tinfoil would work through the glass? The ESP32 comes with capacitive pins, can I use these or do I need to build some amp-stage to boost it? Each touchbutton should be somewhat big, like 15x15cm. Unfortunately radar and sonar can't be used for this.
closed as unclear what you're asking by Marcus Müller, Leon Heller, Olin Lathrop, Transistor, brhans Apr 1 '18 at 15:26
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15cm means that whatever capacitance your potential finger-dielectric-conductor plane plate capacitor has will be extremely small, and so will be the difference between there being a finger or not.
Since all systems on this earth expose noise, I'd be hesitant to say this might theoretically work, and I'm certain to say that no, it won't work with an Arduino.
Trying to help by adding an amplifier betrays a bit of misunderstanding what capacitive sensing is.
All in all: no, won't work. People tend to go optical in that case (it's often easy to see a finger pressed against a flat transparent surface with even minimally cognitive vision). Or, really, use radar technologies, as you've suggested yourself.