Y-shaped microfluidic channel

In the most common jFl-FC conflguration, two aqueous streams (each containing a reactant and a supporting electrolyte) flow side by side down a single Y-shaped microfluidic channel. The anode and the cathode are integrated in the two opposite walls of the channel. The channel with the electrodes is molded in a liquid-tight structure, commonly in poly(dimethylsiloxane) (PDMS) (Figure 18.10). 

Chan et al. (2005), have realised micro fuel cells through an approach that combines thin film materials with MEMS (micro-electro-mechanical system) technology. The membrane electrode assembly was embedded in a polymeric substrate (PMMA) which was micromachined through laser ablation to form gas flow channels. The micro gas channels were sputtered with gold to serve as current collectors. This cell utilized the water generated by the reaction for the humidification of dry reactants (H2 and O2). The peak power density achieved was 315 mW cm (901 mA cm" at 0.35 V) for the H2-O2 system with 20 ml min" O2 supply and H2 at 10 psi in dead ended mode of operation. A Y shaped microfluidic channel is depicted in Fig. 21. 

Fig. 21 The fuel cell system uses a Y-shaped microfluidic channel where two liquid streams containing fuel and oxidant merge and flow between catalyst-covered electrodes without mixing.

Figure 4 A simple y-shaped microfluidic device with two inlet channels and a single outlet channel. The device can be used to mix and react two reagents A and B. By varying the relative volumetric rates (FA and FB) at which the reagents are injected, it is possible to vary the composition of the mixture in the outlet channel. By varying the total flow rate (F=FA + FB), it is possible to control the time the reagents spend in the reaction channel.

Figure 8 A schematic of the reactor used to synthesize the nanoparticles described in this chapter. Cd and Se precursor solutions are stored in two separate syringes and injected at flow rates Ft and F2 into the two inlets of a y-shaped microfluidic device. The microfluidic device rests on a hot plate of variable temperature T. The reagent streams meet at the point of confluence and nucleation, and growth of the particles occurs as they pass along the outlet channel. The emission spectra of the particles so produced are monitored prior to collection at a detection-zone downstream of the chip using a 355-nm Nd YAG laser as an excitation source and a fiber-optic-coupled CCD spectrometer.

Ti02 nanopartides [10-12], NiO nanopartides [13] and various nanopartides of metal oxides [14] are formed in droplets or in a micellar environment. Cottam et al. reported a microfluidic synthesis of small nanorods of titanium oxide by fast mixing of an oleic add solution of tetraisopropoxytitanium (TTIP) with trimethylamine N-oxide dihydrate (TMAO) [15]. Both reaction solutions were mixed by a Y-shaped micro channel structure and conducted through a 40 cm microchannel with an internal channel width of 100 Jim. As a result, bunched assemblies of rod-like titanium dioxide were obtained. The length of the bundles was more than 100 nm and the diameter of the single rods was less than 10 nm. 

This immunoassay is based on the laminar flow in the microfluidic channel. Generally, the large particles such as blood cells are hard to diffuse significantly with time in the microfluidic laminar flow channel, while the fine particles such as ions and small molecules can rapidly diffuse between steams. Yager s group [3] developed a novel microfluidic whole blood immunoassay based on the diffusion, which is called the competitive diffusion immunoassay (DIA). As shown in Fig. 1, a simple Y-shape microstructure was... 

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