This study describes a microfluidic platform with coaxial annular world-to-chip interfaces for high-throughput production of single and compound emulsion droplets, having controlled sizes and internal compositions. The production module consists of two distinct elements: a planar square chip on which many copies of a microfluidic droplet generator (MFDG) are arranged circularly, and a cubic supporting module with coaxial annular channels for supplying fluids evenly to the inlets of the mounted chip, assembled from blocks with cylinders and holes. Three-dimensional flow was simulated to evaluate the distribution of flow velocity in the coaxial multiple annular channels. By coupling a 1.5 cm × 1.5 cm microfluidic chip with parallelized 144 MFDGs and a supporting module with two annular channels, for example, we could produce simple oil-in-water (O/W) emulsion droplets having a mean diameter of 90.7 μm and a coefficient of variation (CV) of 2.2% at a throughput of 180.0 mL h(-1). Furthermore, we successfully demonstrated high-throughput production of Janus droplets, double emulsions and triple emulsions, by coupling 1.5 cm × 1.5 cm - 4.5 cm × 4.5 cm microfluidic chips with parallelized 32-128 MFDGs of various geometries and supporting modules with 3-4 annular channels.

Copper bottom-up deposition in 200 nm trenches by an acid-copper sulfate with only two additives ͓poly͑ethylene glycol͒ ͑PEG͒ and Cl Ϫ ] is achieved. The inhibiting effect of electrodeposition by PEG is strongly related to Cl Ϫ concentration. Secondary-ion mass spectroscopy measurements show that Cl Ϫ is consumed in the electroplating process. The explanation of bottom-up deposition realized in copper superfilling, in which the decrease of Cl Ϫ concentration causes rapid electrodeposition on trench bottoms, is verified experimentally.Copper on-chip interconnection is a current topic in the semiconductor industry. It became possible by copper superfilling 1 of trenches and vias in the damascene process. The superfilling is achieved by the presence of additives in the acid-copper sulfate electroplating bath. Many studies based on the diffusion-adsorption theory 2-11 have been carried out to understand the superfilling process. In those studies, it is assumed that additives inhibit the electrodeposition and are consumed on the plating surface. Due to the diffusional limitation, concentration of additives is decreased in the trench bottom and rapid deposition from the bottom occurs. However, the mole fraction of additive-derived impurities ͑C, O, S, Cl͒ measured by secondary-ion mass spectroscopy ͑SIMS͒ is smaller than the expected value from the diffusion-adsorption based theories. 12-14 So far, poly͑ethylene glycol͒ ͑PEG, Mw about 3000͒ is considered a main inhibitor. The expected diffusion coefficient of the inhibitor is the same order of Cu 2ϩ 8 and it is large for the size of the additives. Then, recent studies showed interest in catalytic additives like bis͑3-sulfopropyl͒disulfide ͑SPS͒ or 3-mercapto-1-propanesulfonate ͑MPSA͒. [15][16][17] In this study, to understand the superfilling mechanism, the inhibition by PEG and Cl Ϫ is carefully investigated by measuring overpotential of an electrode being electroplated. Overpotential MeasurementThe cell for the electroplating experiments is a 500 mL beaker submerged in a water bath at 298 Ϯ 0.5 K. The working electrode ͑WE͒ is a polished platinum disk in an epoxy resin. To assume a one-dimensional flow of current, ions, and additives, the WE is covered by a resin plate which has a cylindrical hole ( ϭ 3 mm). The WE is preplated with copper at 200 A/m 2 for 20 s in the electrolyte of interest before each experiment. After preplating, the electrolyte of the bath is spit out from a thin tube connected to a pump for supplying fresh electrolyte in the hole. To avoid contamination of Cl Ϫ , a copper plate in the cover resin is used as a reference electrode which is expected to work as a stable Cu/CuSO 4 electrode. The composition of the standard electrolyte is 225 g/L CuSO 4 •5H 2 O and 55 g/L H 2 SO 4 . All electrodes are connected to a potentiostat ͑Hokuto Denko, HABF501͒ and constant current is applied for copper electrodeposition on the WE. Figure 1 shows the time variation of overpotential when Cl Ϫ is added to a 3000 Mw PEG containing electroplating bath. The concent...

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We present a microfluidic cross-flowing system for producing biphasic emulsion droplets and non-spherical polymer microparticles. Microfluidic channels on a glass chip comprise a Y-shaped channel so as to form a twophase organic stream of photocurable and non-curable phases, and a T-junction to generate phase-separated droplets in a cross-flowing aqueous stream. The biphasic droplets at equilibrium formed a Janus configuration (partial engulfing) or a core-shell configuration (complete engulfing) consistent with minimizing the interfacial free energies among the three liquid phases, according to the three spreading coefficients. When silicone oil was used as the non-curable phase, monodisperse Janus droplets were generated reproducibly in a one-step process; for e.g., the mean particle size was 119 lm with a coefficient of variation (CV) of 1.9%. Subsequent UV-initiated polymerization yielded monodisperse particles with controlled convex/concave structures, which were tunable through variation of the ratio of the flow rates between the two organic phases. In contrast, when perfluorocarbon fluid, which is more hydrophobic than silicone oil, was used as the non-curable phase, monodisperse core-shell droplets were generated in a two-step regime, leading to the synthesis of cross-linked polymeric shells with a pore on their surfaces. We also investigated how the asymmetric flow configuration influenced droplet formation at the T-junction.