Insulated touch / close proximity sensor?

Hi,

I'm building a LED strip into my bathroom, right next to the bath tub. The electronics together with the LEDs go behind a frosted glass / acrylic pane. I want it to have one or more touch switches for turning on/off, dimming, cycling through colors, that should be usable from the bath tub. For safety reasons, I'd like to use contactless switches built behind the glass/acrylic pane (so a finger touch on the pane is sensed, but no electrical connection is made with the touching finger). Is this possible with capacitive / resistive sensing, or do I need an IR sensor? All projects I have seen using capacitive sensing always required some electrical contact. I foresee problems with an IR sensor due to the glass pane, though.

Thanks a lot in advance,
Björn

Theoretically it's possible, because a thermin works along those lines. However, I haven't seen an DIY application that involves a relatively dense cluster of buttons. That leads me to believe it might be difficult or impractical to achieve.

Capacitive sensors are normally (nearly always) used electrically isolated from human contact. Some things that might help are:

  • keep the glass thin, if possible
  • sensor pads not too small
  • if you get too much cross talk, add separation or a ground line between the buttons (not electrically connected)