title: Discrete electric field mediated droplet splitting in microchannels: Fission, Cascade, and Rayleigh modes.
abstract: Numerical simulations supplemented by experiments together uncovered that strategic integration of discrete electric fields in a non-invasive manner could substantially miniaturize the droplets into smaller parts in a pressure driven oil-water flow inside microchannels. The Maxwell's stress generated from the electric field at the oil-water interface could deform, stretch, neck, pin, and disintegrate a droplet into many miniaturized daughter droplets, which eventually ushered a one-step method to form water-in-oil microemulsion employing microchannels. The interplay between electrostatic, inertial, capillary, and viscous forces led to various pathways of droplet breaking, namely, fission, cascade, or Rayleigh modes. While a localized electric field in the fission mode could split a droplet into a number of daughter droplets of smaller size, the cascade or the Rayleigh mode led to the formation of an array of miniaturized droplets when multiple electrodes generating different field intensities were ingeniously assembled around the microchannel. The droplets size and frequency could be tuned by varying the field intensity, channel diameter, electrode locations, interfacial tension, and flow ratio. The proposed methodology shows a simple methodology to transform a microdroplet into an array of miniaturized ones inside a straight microchannel for enhanced mass, energy, and momentum transfer, and higher throughput.
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Guwahati, India.
authors.forename: Joydip
authors.initials: J
authors.lastname: Chaudhuri
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Guwahati, India.
authors.forename: Seim
authors.initials: S
authors.lastname: Timung
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Guwahati, India.
authors.forename: Chola Bhargava
authors.initials: CB
authors.lastname: Dandamudi
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Guwahati, India.|Centre for Nanotechnology, Indian Institute of Technology, Guwahati, India.
authors.forename: Tapas Kumar
authors.initials: TK
authors.lastname: Mandal
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology, Guwahati, India.|Centre for Nanotechnology, Indian Institute of Technology, Guwahati, India.
authors.forename: Dipankar
authors.initials: D
authors.lastname: Bandyopadhyay
mesh_terms: D003198:Computer Simulation; D004560:Electricity; D046210:Microfluidic Analytical Techniques; D008962:Models, Theoretical; D012827:Silicone Oils / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D012827:Silicone Oils; D014867:Water
keywords: Droplets; Electric field; Microchannel; Miniaturization; Multiphase flow