This is an example of allocation of the layers in a four-layer PCB. The top layer is where the actual sensing pads are. The Middle 1 layer can be used for routing, making sure that the separation between this layer and the top is at least ten mils. The Middle 2 layer can be used for either device routing or the sensor pad routing. The Bottom layer is reserved for device routing. As recommended also for the Top layer, all the empty space should be filled with a mesh ground for protection against noise. Following these hardware recommendations in the actual layout when setting up an application will help ensure that issues with noise or too high intrinsic capacitance will not occur.