Fick's law

Anyone knows how do we derive Fick's law of diffusion applied to chemical sensing;

I=JmF

from I=nAve

where :
J=flux
m=number of electrons
F=faraday constant
v=speed of particles
n=number of charge carriers/vol
A= cross-sectional area of sensor(electrode)
e=charge of an electron


Any help will be greatly appreciated.Thanks