Virginia TechRoy, T.Sinha, AshokChakraborty, ShibajiGanguly, RanjanPuri, Ishwar K.2014-04-242014-04-242009-02-01Roy, Tamal; Sinha, Ashok; Chakraborty, Sayan; et al., "magnetic microsphere-based mixers for microdroplets," Phys. Fluids 21, 027101 (2009); http://dx.doi.org/10.1063/1.30726021070-6631http://hdl.handle.net/10919/47639While droplet-based microfluidic systems have several advantages over traditional flow-through devices, achieving adequate mixing between reagents inside droplet-based reactors remains challenging. We describe an active mixing approach based on the magnetic stirring of self-assembled chains of magnetic microspheres within the droplet as these stirrers experience a rotating magnetic field. We measure the mixing of a water-soluble dye in the droplet in terms of a dimensional mixing parameter as the field-rpm, fluid viscosity, and microsphere loading are parametrically varied. These show that the mixing rate has a maximum value at a critical Mason number that depends upon the operating conditions.application/pdfen-USIn CopyrightDropsDyesMagnetohydrodynamicsMicrofluidicsMixingViscosityParamagnetic particlesDigital microfluidicsAnalysis systemsFieldNanoparticlesEnhancementCapillariesDevicesChainsScaleArticle - Refereedhttp://scitation.aip.org/content/aip/journal/pof2/21/2/10.1063/1.3072602https://doi.org/10.1063/1.3072602