Here we can see how important it is to have protection against Electrostatic Discharge to avoid damage to sensitive device. 

As I stand up, my body get charged and this charge is kept isolated by the shoes and vinyl floor.
My right foot has an ESD Heel Grounder to short cut the shoes (by a 1 Mega ohm resistor), but the vinyl floor still keep the charge in my body.

We can see that, as soon as I step on the ESD rubber mat, the electrostatic charge is discharged to ground via Heel Grounder and grounded mat. Now I can touch the grounded electronic circuit.
The left foot on grounded mat does not have the same safety effect.
The buzzer is switched by a FET transistor, in which the gate is connected to a wired antenna to detect the electric field.