Microfluidic separation processes using the thermodiffusion effect

Abstract

The numerical and experimental results presented in this work show that a relatively small temperature gradient (5K), has great potential to generate a separation in interesting mixtures for biological purpose. In fact, it improves molecular diffusion separation process of a protective cryo (10% of dimethyl sulfoxide (DMSO) in phosphate buffered saline (PBS)) for cryopreserved cells, by 10%. This separation process was analyzed both numerically and experimentally, for which it was necessary to determine experimentally the thermophysical and transport properties of the mixture of 10% of DMSO in PBS. Experimental tests were done in a microdevice with a working section of 500μ m × 25 mm and a length of 75 mm, which was designed, constructed and first of all validated with the mixture of reference H2O-Isopropanol at a mass fraction of 50%. Experimental test with the protective cryo were done with in flow rates between 1000μL/min and 4000μL/min. The results confirm that the effect of thermodiffusion must be considered in handling processes of biological fluid mixtures because the existence of a thermal gradient could improve the efficiency of the separation process in microdevices.