I've seen some DIY capacitive touch sensor projects where the sensors themselves are strips of aluminum or copper soldered to a non-grounded wire, where the user touches these strips directly with their finger to be sensed.
I'm a bit unclear as to why this design is considered "capacitive". My understanding of stuff like glass touchscreens is that there is a cathode on one end of the glass, and when a user touches the glass it forms the anode, with the glass serving as the dielectric.
But if the aluminum or copper strip is the cathode, and the finger touches it directly – wouldn't this be a resistive phenomenon? I thought capacitance implied a separation of two charged surfaces.
Best Answer
OP's Mathworks link has a link to Ardunio playground Capacitive sensing library link. This link mentions a few points (emphasis mine)
In fact, according to them, resistance is bad.
The page gives even more helpful guidelines.
In short, the answer to your question is that, it is dependent on the specific circuit. In the link you provided, the circuit still depends on capacitance and resistance is detrimental to its working.