Microfluidic approach for rapid multicomponent interfacial tensiometry

Abstract

We report a microfluidic instrument to rapidly measure the interfacial tension of multi-component immiscible liquids. The measurement principle rests upon the deformation and retraction dynamics of drops under extensional flow and was implemented for the first time in microfluidics (S. D. Hudson et al., Appl. Phys. Lett., 2005, 87, 081905 (ref. )). Here we describe in detail the instrument design and physics and extend this principle to investigate multicomponent mixtures, specifically two-component drops of adjustable composition. This approach provides fast real-time sigma measurements (on the order of 1 s), the possibility of rapidly adjusting drop composition and utilizes small sample volumes (approximately 10 microL). The tensiometer operation is illustrated with water drops and binary drops (water/ethylene glycol mixtures) in silicone oils. The technique should be particularly valuable for high-throughput characterization of complex fluids.

Production of uniform droplets using membrane, microchannel and microfluidic emulsification devices

“…The growth of microfluidic drop generation processes in the past decade was driven by a rising number of applications that can take advantage of precision generation and manipulation of droplets on a microscale (Atencia and Beebe, 2005). These applications range from capillary electrophoresis (Kameoka et al, 2001) and immunoassays (Hatch et al, 2001) to cellomics (Andersson and van den Berg, 2003;Wu et al, 2011), proteomics (Figeys and Pinto, 2001), DNA analysis (McClain et al, 2001), and interfacial tensiometry (Cabral et al, 2006).…”

Shear and dilational interfacial rheology of surfactant-stabilized droplets

“…By balancing this (known) force with the interfacial restoring force, the interfacial tension can be determined simply by measuring the droplet shape and its position as a function of time as described in detail previously. [11,12,17] This acceleration occurs during a period typically of approximately 30 ms. This is very short compared to the age of the interface (typically seconds …”

“…[11,12,15,16] Microfluidic devices were mounted on an Olympus IX71 inverted microscope fitted with an automated translating XY stage (Prior H107).…”

“…Furthermore, the channel geometry can be altered easily to prescribe the desired flow. In past work, microfluidic devices similar to those employed here were used to measure the interfacial tension of multicomponent immiscible liquids [11] and probe mass transport and interfacial kinetics from droplets during a liquid-phase extraction process. [12] A suspended droplet in flow travels at a velocity that is intermediate to neighboring velocities in the surrounding fluid, thus causing the droplet fluid to circulate.…”

Interfacial Phenomena and Fluid Control in Micro/Nanofluidics

“…The in situ interfacial tension measurement remains a significant challenge, although some attractive image-based methods, [132][133][134] a light scattering method, 135,136 and an electrochemical method 137 have been reported. These new challenges are expected to advance the science and technology in this field in the next years.…”