TTP223B Touch Sensor IC - Large Area Detection

[kolbep]

Hi All,
Busy with another strange one, and my google-fu is not too strong today.

I have a Transparent Perspex Panel (Acrylic for the Non-Yanks)(Approx 900mm x 450mm x 5mm), on that perspex panel i have a 'chrome' sticker. It is not a metallic sticker, just a shiny one. (I tested - It is non conductive).

I would like for a person to be able to touch the 'Chrome' part of the panel, and the RPI responds to that touch.
So I ordered some TTP223B Modules. (Man those things are Tiny).

I tried putting it on the rear of the acrylic, and it would not detect touch through the acrylic, but a touch on the Modules board itself did detect.

Is there a way to expand this modules sensitivity and area, so that a touch anywhere on the panel (or even a decent sized area of the panel) will trigger, or is there another way for me to go about this.

Thinking to myself, maybe use a Piezo Transducer, but then i have to tell them to knock or hit the panel.  Ideally I would prefer the Cap Touch, but whatever the best solution is

Thanks
P

[vintagemaniac]

To increase the sensitivity you should reduce (or remove completely) the 30 pF cap on the board.

[Microcheap]

To increase the sensibility of the TTP223B try to use a larger sensor pad connected to pin 3 of the IC (I used a cooper foil pealed off from a PCB clad, soldered a wire to it and then I insulated with kapton tape).
As pointed by @vintagemaniac, a capacitor from pin3 to ground will reduce the sensibility of the sensor.