Liquid diffusion measurement in micro/mini channels from full-field digital phase measurement interferometry (PMI)

This paper considers division of amplitude interferometry as a means to extract fluid information from micro-systems. Initially the phase measurement technique is analysed and the measurement limitations of mixing measurement are assessed. Accurate phase measurements are then made of the concentration in a 3 dimensional channel flow. A mini sized channel with two fluid flows at Reynolds numbers of 0.848 and 0.0848 is numerically analysed. The same channel is experimentally tested and the results for the mixing concentration gradients in channel flow are compared with those obtained numerically. The requirement for experimental measurement for accurate measurement of binary liquid diffusion is observed by the variation between experimental and numerical results. The diffusion coefficient measurement verifies PMI as a means of mixture measurement, or more broadly as a phase measurement technique for small-scale, or micro scale, fluidic analysis. PMI's potential is finally discussed as a measurement technique for concentration, and hence fluidic analysis of micro channel mixing.