Oil-in-Water fL Droplets by Interfacial Spontaneous Fragmentation and Their Electrical Characterization

Langmuir. 2019 Apr 9;35(14):4936-4945. doi: 10.1021/acs.langmuir.8b04316. Epub 2019 Mar 27.

Abstract

Inkjet printing is here employed for the first time as a method to produce femtoliter-scale oil droplets dispersed in water. In particular, picoliter-scale fluorinated oil (FC40) droplets are printed in the presence of perfluoro-1-octanol surfactant at a velocity higher than 5 m/s. Femtoliter-scale oil droplets in water are spontaneously formed through a fragmentation process at the water/air interface using minute amounts of nonionic surfactant (down to 0.003% v/v of Tween 80). This fragmentation occurs by a Plateau-Rayleigh mechanism at a moderately high Weber number (101). A microfluidic chip with integrated microelectrodes allows droplets characterization in terms of number and diameter distribution (peaked at about 3 μm) by means of electrical impedance measurements. These results show an unprecedented possibility to scale oil droplets down to the femtoliter scale, which opens up several perspectives for a tailored oil-in-water emulsion fabrication for drug encapsulation, pharmaceutic preparations, and cellular biology.

Publication types

  • Research Support, Non-U.S. Gov't