Xm. Zhang et al., Investigation of molecular diffusion in hydrogel by electronic speckle pattern interferometry, J PHYS CH B, 103(29), 1999, pp. 6069-6074
The technique of real-time electronic speckle pattern interferometry (ESPI)
is proposed to study the diffusion process of surfactants and proteins in
gels. The diffusion coefficient is simply and directly determined from the
interferograms. The experiments were carried out on a series of surfactants
as well as on a myoglobin diffusion in agarose gels. The agreement of the
diffusion coefficient values obtained from ESPI with those obtained by elec
trical conductance: measurement or the reported data demonstrates the usefu
lness of the method. Moreover, spatial distribution of refractive index cha
nge in the gel can be determined by phase evaluation. Fick's law for diffus
ion is utilized to analyze the spatial distribution of the diffuser concent
ration curves in gel, which are compared with experimental data. We find th
at the agarose gel in surfactant solution shrinks slightly, which increases
the density of the gel and leads to the additional refractive index change
. The effect of gel shrinking to surfactant diffusion is discussed, and the
distribution of density variation of the gel with time is evaluated.