A simple touch sensor you can make from the black foam used to protect semiconductor devices. Use two metal sheets to squeeze a piece of foam, finish with a rubber ring or a Scotch tape. See how the resistance varies with pressure.
Capacitive sensors require thin-film on plastic or glass foil, and an AC signal source .
How can one have "a doubt" about something he knows nothing about?
Every person having anything to do with electronics knows what the "black foam" is. Find such person and you will see.
Capacitive sensors usually do not work in DC circuits, they need AC circuits to function.