Hey everyone,
So I'm wanting to do a simple capacitive touch sense switch (just off or on) using the Teensy. I'm currently designing the PCB pads and wondering I can leave the soldermask on? This would definitely be a preference for me, so I don't show any bare-copper and can choose the soldermask color.

Attached is a screenshot of my PCB touch pad I'm working on, it is ~ .75" x .5".

Click image for larger version. 

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One of the traces is going to go to the teensy and the other is ground. In my first tests (just using copper tape), I get a much stronger output from the capacitance sense pin if my finger is also touching ground. Maybe this is because my application is not tied to mains earth.

Interestingly, on my tests I get a much better signal to noise ratio using the generic arduino CapacitiveSensor library compared to the Teensy specific one.