High-Order Multiple Emulsions Formed in Poly(dimethylsiloxane) Microfluidics

A simple system to form monodisperse high-order multiple emulsions, which combines the control of microfluidic drop formation with the scalability of lithographically fabricated devices, was studied. The devices were coated with a photoreactive sol-gel within 15 minutes after plasma bonding to spatially control wettability. The devices were filled with the photoreactive sol-gel mixture and heated with a hotplate set to 225 °C, this vaporizes the solvent in the mixture and deposits the coating. The multiple emulsions was formed by injecting water and fluorocarbon oil with surfactants into the linear drop maker arrays. The diameter distributions of both the inner and the outer drops were measured for the double emulsions, and plotted individually. It was concluded that lithographically fabricated devices combine the precision and scalability necessary to form the emulsions with controlled morphology and with high monodispersity.