capacitive touch not working with 2.5mm sheet on touch side terminal of 10Mohm

Hello guys,

I tried the capacitive touch using library available in this website and its working perfectly.

Since my pcb requires 5 switches of same type i added it.

Now the issue is when i covered 2.5mm thickness sheet on pcb ...the capacitive touch isn't working at all
i have used 10Mohm resistor without the capacitor at the touch side terminal of the 10Mohm resistor.

but when i remove the 2.5mm thickness and touch using bare fingers its working.!!!

can anyone tell me how to resolve this issue?
please its very much required.

Rakshith_KR:
but when i remove the 2.5mm thickness and touch using bare fingers its working.!!!

Well, there you have your answer - that is, assuming your unspecified sheet is of non-conductive material.
It seems your sensors are not sensitive enough to detect proximity, but require touch.

Possible solutions:

  • increase the sensitivity of your sensors (software and/or hardware wise - can't give suggestions as you didn't tell anything about the sensors themselves, nor the software that reads them),
  • create a conductor from the top of the sheet to the sensor below it.

You need 2 plates for every capacitive sensor, one connected to Gnd, and one connected to the I/O pins. Else you risk to activate multiple sensors at the same time, poor sensitivity and random behaviour of the sensors.

You can surround and separate every sensor by a common Gnd plane on the PCB. Turn the copper side towards the operator, and cover it by thinner material.