Advice For a Touch Sensor

I want to build a pair of "friendship lamps". I'm going to model this lamp after this commercial example. I need a discreet way to activate my lamp. In the linked example it appears the user just touches the wood.

  1. How exactly would you all guess the linked example is detecting touches through wood? Force sensor?
  2. Any other ideas/suggestions to go about detecting touches discreetly and reliably?

[edit]
very relevant thread: Sensing touch through a piece of wood - Project Guidance - Arduino Forum
I'll explore this route for my project unless anyone has further suggestions.

TTP223 based capacitive sensor will work wonders, it happily reads through a few mm of wood, plastic, glass, etc (but after a few seconds it recalibrates and the touch is not detected any more). So one touch for on, a next touch for off. No very long touch possible.

Good to know, thank you. That drawback shouldn't be an issue for my purposes.