Authors: C. Pulido de Torres, E. Amici, A. Gallarino, M. Da Silva, F. Jousse
Affilation: Unilever, United Kingdom
Pages: 686 - 689
Keywords: droplets, emulsion, complex structures
We present Microfluidic technology applied to the production of monodisperse emulsion in a food context. We investigate the effect of surfactants and microdevice geometry on drop size and robust production regimes.<br> <br>Minimum drop size achievable in a microdevice is influenced by microdevice geometry. An asymptotic minimum size is observed and found to be half of width of the channel, for in-channel break geometries like T junctions, and 80% of the aperture for flow focusing geometries. <br> <br>Drop sizes decrease continuously with increasing concentration of surfactant although for high concentrations the monodispersity is lost.<br> <br>A microfluidic device can produce monodisperse, polydisperse emulsion or jet (parallel flow of fluids). Surfactant addition modifies the boundaries of the different production regions. For a surfactant free system the monodisperse production region is considerably smaller, almost half, than when the surfactant is added. <br> <br>The boundary between jetting and drop production regimes also changes, for each geometry, being noteworthy the increase of drop production region for a Pi junction with respect a flow focusing geometry.<br> <br>Finally is was found that there seem to be a relationship between drop size and a magnitude related with the capillary number, defined by Q/s (Q, continuous phase flow rate, s interfacial tension).