  We present a microfluidic method leading to accurate measurements of the
mutual diffusion coefficient of a liquid binary mixture over the whole solute
concentration range in a single experiment. This method fully exploits solvent
pervaporation through a poly(dimethylsiloxane) (PDMS) membrane to obtain a
steady concentration gradient within a microfluidic channel. Our method is
applicable for solutes which cannot permeate through PDMS, and requires the
activity and the density over the full concentration range as input parameters.
We demonstrate the accuracy of our methodology by measuring the mutual
diffusion coefficient of the water (1) $+$ glycerol (2) mixture, from
measurements of the concentration gradient using Raman confocal spectroscopy
and the pervaporation-induced flow using particle tracking velocimetry.
