Fick's law can be used to measure flux (J).
For example when the movement of ions is in a non-equilibrium state, net movement of solute across the membrane.
J=P x C
J= Flux (Units= Moles/CM/Second)
P= Permeability (Units= CM/Second)
C= Concentration Gradient for uncharged solute across the membrane (Units= Moles/ CM)
P= 20 moles/cm/second
C= 58 moles/cm
J= 20x58= 1160 moles/cm/second
- ↑ Steven L. Jacques, Scott A. Prahl  Fick's 1st law of diffusion [Internet], Oregon Graduate Institute, ECE532 Biomedical Optics. Available from http://omlc.ogi.edu/classroom/ece532/class5/ficks1.html [Accessed 20th October 2013]