Microfluidic production of monodispersed microspheres and microcapsules for photocatalytic water treatment and CO2 capture

Microfluidic production of monodispersed microspheres and microcapsules for photocatalytic water treatment and CO2 captur

Microfluidic production of microspheres and microcapsules for photocatalytic water treatment and CO2 capture

Microfluidic production of microspheres and microcapsules for photocatalytic water treatment and CO2 captur

Evidence of slippage breakdown for a superhydrophobic microchannel

© 2014 AIP Publishing LLC.A full characterization of the water flow past a silicon superhydrophobic surface with longitudinal micro-grooves enclosed in a microfluidic device is presented. Fluorescence microscopy images of the flow seeded with fluorescent passive tracers were digitally processed to measure both the velocity field and the position and shape of the liquid-air interfaces at the superhydrophobic surface. The simultaneous access to the meniscus and velocity profiles allows us to put under a strict test the no-shear boundary condition at the liquid-air interface. Surprisingly, our measurements show that air pockets in the surface cavities can sustain non-zero interfacial shear stresses, thereby hampering the friction reduction capabilities of the surface. The effects of the meniscus position and shape as well as of the liquid-air interfacial friction on the surface performances are separately assessed and quantified

Microfluidic production of poly(1,6-hexanediol diacrylate)-based polymer microspheres and bifunctional microcapsules with embedded TiO2 nanoparticles

Application of TiO2 as a photocatalyst and UV protector is restricted by the difficulties in the recovery of TiO2 nanoparticles after water treatment. In this work, TiO2 nanoparticles (Degussa P25) were immobilised within easily recoverable poly(1,6-hexanediol diacrylate)-based polymer microspheres produced by on-the-fly photopolymerisation of microfluidically generated droplets. Due to fast polymerisation reaction, TiO2 was uniformly distributed within the polymer network. The transformation of double bonds in terminal vinyl groups of 1,6-hexanediol diacrylate (HDDA) monomer into single bonds during photopolymerisation was confirmed by Fourier Transform infrared spectroscopy. The microspheres containing 0.5 wt% TiO2 embedded in a poly(HDDA) matrix degraded 80% of methylene blue from 1 ppm aqueous solution in 9 h under UV light irradiation at 365 nm. The microspheres could easily be separated from water and used in repeated cycles without any loss in photocatalytic activity. The inclusion of TiO2 within a polymer matrix increased the thermal degradation temperature of the material from 364 to 389 oC. Bifunctional microcapsules consisted of aqueous or liquid paraffin core enclosed within a TiO2/poly(HDDA) composite polymer shell were also prepared. The fluorescent dye calcein was encapsulated in the core with 100 % efficiency

An integrated microfluidic chip for generation and transfer of reactive species using gas plasma

Reactive species produced by atmospheric pressure plasma (APP) are useful in many applications including disinfection, pretreatment, catalysis, detection and chemical synthesis. Most highly reactive species produced by plasma, such as ·OH, 1O2 and , are short-lived; therefore, in-situ generation is essential to transfer plasma products to the liquid phase efficiently. A novel microfluidic device that generates a dielectric barrier discharge (DBD) plasma at the gas-liquid interface and disperses the reactive species generated using microbubbles of ca. 200 µm in diameter has been developed and tested. As the bubble size affects the mass transfer performance of the device, the effect of operating parameters and plasma discharge on generated bubbles size has been studied. The mass transfer performance of the device was evaluated by transferring the reactive species generated to an aqueous solution containing dye and measuring percentage degradation of the dye. Monodisperse microbubbles (polydispersity index between 2 - 7%) were generated under all examined conditions but for gas flow rate exceeding a critical value, a secondary break-up event occurred after bubble formation leading to multiple monodisperse bubble populations. The generated microbubble size increased by up to ~ 8% when the device was operated with the gas plasma in the dispersed phase compared to the case without the plasma due to thermal expansion of the feed gas. At the optimal operating conditions, initial dye concentration was reduced by ~60% in a single pass with a residence time of 5-10 s. This microfluidic chip has the potential to play a significant role in lab-on-a-chip devices where highly reactive species are essential for the process. </p

Solute-driven colloidal particle manipulation in continuous flows past grooved microchannels [abstract]

Solute-driven colloidal particle manipulation in continuous flows past grooved microchannels [abstract

Direct manipulation of liquid ordered lipid membrane domains using optical traps

Multicomponent lipid bilayers can give rise to coexisting liquid domains that are thought to influence a host of cellular activities. There currently exists no method to directly manipulate such domains, hampering our understanding of their significance. Here we report a system that allows individual liquid ordered domains that exist in a liquid disordered matrix to be directly manipulated using optical tweezers. This allows us to drag domains across the membrane surface of giant vesicles that are adhered to a glass surface, enabling domain location to be defined with spatiotemporal control. We can also use the laser to select individual vesicles in a population to undergo mixing/demixing by locally heating the membrane through the miscibility transition, demonstrating a further layer of control. This technology has potential as a tool to shed light on domain biophysics, on their role in biology, and in sculpting membrane assemblies with user-defined membrane patterning

3D arrays of super-hydrophobic microtubes from polypore mushrooms as naturally-derived systems for oil absorption

Porous materials derived from natural resources, such as Luffa sponges, pomelo peel and jute fibres, have recently emerged as oil adsorbents for water purification, due to their suitability, low environmental impact, biodegradability and low cost. Here we show, for the first time, that the porosity of the fruiting body of polypore mushrooms can be used to absorb oils and organic solvents while repelling water. We engineered the surface properties of Ganoderma applanatum fungi, of which the fruiting body consists of a regular array of long capillaries embedded in a fibrous matrix, with paraffin wax, octadecyltrichlorosilane (OTS) and trichloro(1H,1H,2H,2H-perfluorooctyl)silane. Morphological and wettability analyses of the modified fungus revealed that the OTS treatment was effective in preserving the 3D porosity of the natural material, inducing super-hydrophobicity (water contact angle higher than 150°) and improving oil sorption capacity (1.8-3.1 g/g). The treated fungus was also inserted into fluidic networks as a filtration element, and its ability to separate water from chloroform was demonstrated

Mechanical characterization of ultralow interfacial tension oil-in-water droplets by thermal capillary wave analysis in a microfluidic device

Measurements of the ultralow interfacial tension and surfactant film bending rigidity for micron-sized heptane droplets in bis(2-ethylhexyl) sodium sulfosuccinate-NaCl aqueous solutions were performed in a microfluidic device through the analysis of thermally driven droplet interface fluctuations. The Fourier spectrum of the stochastic droplet interface displacement was measured through bright-field video microscopy and a contour analysis technique. The droplet interfacial tension, together with the surfactant film bending rigidity, was obtained by fitting the experimental results to the prediction of a capillary wave model. Compared to existing methods for ultralow interfacial tension measurements, this contactless, nondestructive, all-optical approach has several advantages, such as fast measurement, easy implementation, cost-effectiveness, reduced amount of liquids, and integration into lab-on-a-chip devices

Multiplexed droplet Interface bilayer formation

We present a simple method for the multiplexed formation of droplet interface bilayers (DIBs) using a mechanically operated linear acrylic chamber array. To demonstrate the functionality of the chip design, a lipid membrane permeability assay is performed. We show that multiple, symmetric DIBs can be created and separated using this robust low-cost approach