Jump to Main Content
Oil-in-Water fL Droplets by Interfacial Spontaneous Fragmentation and Their Electrical Characterization
- Arrabito, Giuseppe, Errico, Vito, De Ninno, Adele, Cavaleri, Felicia, Ferrara, Vittorio, Pignataro, Bruno, Caselli, Federica
- Langmuir 2019 v.35 no.14 pp. 4936-4945
- air, droplets, electric impedance, emulsions, microelectrodes, nonionic surfactants, oils, organ-on-a-chip, polysorbates
- 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.