Tuning between Water-in-Oil and Oil-in-Water Microfluidics

Introduction:

Two-phase flow, which can be either flow of oil droplets suspended in a continuous water phase or water droplets suspended in a continuous oil, has many potential applications[1]. Microfluidic technology is becoming a very reliable method to make monodisperse droplet suspensions[2]. In the BIOS group we use glass and silicon to make micro/nanofluidic chips for two-phase flow.

Oil in water (O/W) flow is generally obtained in untreated glass or silicon chips due to the channel wettability. The reversion of O/W to water in oil (W/O) flow in the same microfluidic device can be realized by surface treatment as shown in the Figures.

Figure 1 O/W flow in the hydrophilic glass-silicon chip (oil is dark and water light)

Figure 2 W/O flow in the same chip with surface modified channels

Project description:

The project is to study W/O and O/W emulsion generation and the conditions for on-chip emulsion reversion in microfluidic devices by:

(1)	surface modification

(2)	selection of suitable surfactants (HLB value)

(3)	combination of (1), (2) and flow ratio of water to oil phase.

Contact information:

Lingling Shui / Jan C.T.Eijkel

MESA+ Institute for Nanotechnology

University of Twente

P.O. Box 217

7500 AE Enschede

The Netherlands

Email: L.shui@ewi.utwente.nl

Phone: 0031-053-489-2722

References

1. Shui, L., J.C.T. Eijkel, and A. van den Berg, Multiphase flow in microfluidic systems - Control and applications of droplets and interfaces. Advances in Colloid and Interface Science. 2007 133: p.35-49

2. Joanicot, M. and A. Ajdari, Droplet control for microfluidics. Science, 2005. 309(5736): p. 887-888.