Oxygenation is a key parameter in tumor spheroid culturing. This work reports on the study of oxygen concentration and gas exchange dynamics in two-phase microfluidic droplet systems. Initial measurements of oxygen in single, oilcovered aqueous droplets in micro-wells show the feasibility of droplet-based sensing. We further introduce on-chip generation and trapping of individual droplets with ...

A mononuclear compound droplet generation system has been developed based on both the hydrodynamic flow focusing and the solvent exchange method. The results show that the current system provided excellent control over the jet diameters of individual fluid consisting of the compound jet and the resultant compound drop diameters. The compound droplets were controlled in the range of 46–90 μm. Th...

We investigate the droplet size distributions and concentrations produced by an aerosol generator driven by a high velocity air jet delivered in cross flow to an oil tube at Mach numbers of 0.1-1.0, and Weber numbers based on the air flow parameters between 1000 to 40000. Measured Sauter mean droplet diameters (SMD) from 1μm to 3.5μm were determined by an Electronic Low Pressure Impactor over t...

Proteins that fail to fold or assemble in the endoplasmic reticulum (ER) are destroyed by cytoplasmic proteasomes through a process known as ER-associated degradation. Substrates of this pathway are initially sequestered within the ER lumen and must therefore be dislocated across the ER membrane to be degraded. It has been proposed that generation of bicellar structures during lipid droplet for...

Conventional droplet generation approaches in digital microfluidics show ~10% variation in droplet volumes and are restricted to creating only small volumes. In this work, we demonstrate a new approach for splitting sample volumes precisely by gradually ramping down voltage, in place of abruptly switching off electrodes. This allows us to eliminate hydrodynamic instabilities responsible for var...

Spontaneous emulsification through microchannels, in which droplets are formed due to Laplace pressure difference, is a relatively new technique for preparing monodisperse emulsions. The technique is extremely suited for products containing temperature and shear sensitive ingredients and for products that require high monodispersity; however, industrial application is still not possible due to ...

The first lab-on-chip system for picoliter droplet generation and PCR amplification with real-time fluorescence detection has performed PCR in isolated droplets at volumes 106 smaller than commercial real-time PCR instruments. The system utilized a shearing T-junction in a silicon device to generate a stream of monodisperse picoliter droplets that were isolated from the microfluidic channel wal...

Directional and controllable transportation of microdroplets is critical for emerging micro- and nanotechnology, in which the conventional mechanical energy generation is not applicable. This Letter shows that an aqueous microdroplet can be charged for controlled motion in electrostatic potential, which was created by differentiating pH, between two oil/water interfaces. The directional motion ...

We describe a method to induce by light a reversible switch from a continuous two-phase laminar flow to a droplet generating regime, in microfluidic devices with a usual water-in-oil flow focusing geometry. It consists in adding a photosensitive surfactant to the aqueous phase to modulate using light the interfacial energy between flowing liquids and the microfluidic substrate. We show that UV ...

We report detailed nucleation studies on the liquid-to-solid transition of hexadecane using nearly monodisperse hexadecane-in-water emulsions. A careful consideration of the kinetics of isothermal and nonisothermal freezing shows deviations from predictions of classical nucleation theory, if one assumes that the emulsion droplet population is homogeneous. Similar deviations have been observed p...