In the entry above it is not indicated how one gets the transported
charge from the difference in the Fermi levels of the two materials.
Here is the method I used. You will notice that the closest separation
of the two surfaces actually drops out of the calculation for the
charge transported but not for the sticking force.

The physics idea is that when the viton touches the fused silica it
deforms (much like the Helmholtz calculation for the contact area
between a sphere and a flat surface). The deformation is d0. The 
radius of the viton piece is R so that the radius squared of the
contact area is 2*d0*R. The contact area is then

              A = pi*2*d0*R

The charge in the material with the larger Fermi energy tunnels
through to the other material. The two contacting surfaces can
be thought of being a parallel plate capacitor with the potential
difference V(fermi), area A and spacing d0. The charge on each material
becomes

             Q = C*V(fermi) = 2*pi*V(fermi)*R

(I am using God's units no epsilon zero). Using the values

    V(fermi) = 20 volts => 6 x 10^-2 statvolts

    R        =  3 x 10^-1 cm

Q becomes 1 x 10^-1 esu => 3 x 10^-11 coulombs 

The formula in the prior entry for the average force

            a
    [F] = ------  
            x^2

a = q^2 = 1 x 10^-2 esu^2