Diffusivity measurement using compact low cost field portable device based on light deflection

Imaging and measurement of diffusion process in liquid solutions is a challenging and interesting problem. Especially the mixing of binary liquid solutions in real-time provides an insight into the physics of diffusion as well as leads to measurement of diffusion coefficient, which is the most important parameter of a diffusing liquid solution. Accurate measurement of diffusion coefficient is important in areas ranging from oil extraction to pollution control. Interferometric methods provides very accurate measurement of diffusion coefficients albeit they impose very stringent optical conditions. Here we describe the development of a compact, easy to implement, easy to use and inexpensive device for imaging and quantification of the diffusion process. This technique does not require the stringent optical conditions of interferometric techniques. It computes the diffusivity values by measuring the amount of deflection happening to a line pattern printed on a paper and projected through the sample cell. The measured diffusivity values varied by less than 1%, with the values of diffusivities reported in literature.