This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.For many encapsulation applications such as nutrients, cells and drugs, large core-shell drops are
required. Conventional confined microfluidic devices are limited to a rather small sized (< 1mm) droplets
because of difficulties associated with phase separation at low flow rates. We report a microfluidic device
which can produce such large range of drop sizes (~200 Am- 6 mm) with varying shell thickness (~1 Am- 1
mm) under the maximum influence of buoyancy, which has so far remained unexplored. The existing
physical model for single drop formation is extended for the core-shell drop. The facile nature of working
with such systems means scale up would be easy
