I need to achieve "contact-less" jack-detect for a 3.5mm audio plug. i.e. the tip, ring, sleeve must all be galvanically isolated from the rest of the system, but still being able to know if something is inserted in the jack...
So I was thinking, would it be possible to use either Cap-touch or Inductance-based sensing by wiring up some magic just under the surface-mounted audio-jack together with a PSoC!?
I think you will have to make the tests yourself. Take a CapSense ready development kit as the CY8CKIT-044 and use a pin for an additional button input. I have made good experiences with conductive ink on overhead foil to build isolated buttons on-the-fly.
CapSense tuner will help you to configure sensitivity etc.