Micro beads

Adding additional surface. Whilst a high ratio of surface to volume is inherent in an empty/open micro-channel, this characteristic may be further pronounced by packing micro-beads in the channel (He et al. 2004). The introduction of beads within microchannels can introduce some practical difficulties, but a number of successful applications using this type of methodology have been described (He et al. 2004 Nikbin and Watts 2004). 

Mixed protein/polysaccharide micro-beads have also been found to be promising delivery vehicles for immobilized bifidobacteria (Guerin et al, 2003). Such micro-beads were made by a transacylation reaction involving the formation of amide bonds between protein and alginate (Levy and Edwards-Levy, 1996). This produces a membrane on the bead surface, protecting the immobilized bifidobacteria against both the very acidic conditions (pH 1-2) and the pepsin activity in the stomach. 

Magnetic Micro-bead Mixing Most Relevant Citations... 

Mixer 23 [M 23] Magnetic Micro-bead Micro Mixer... 

This magnetic micro-bead mixer relies on a dynamic mixing principle, based on stirring of externally driven small particles in a small mixing chamber [106,107]. Magnetic beads made of nickel were enclosed in this chamber. The externally stimulated bead motion resulted in rapid homogenization of the solutions to be mixed. 

Mixer 86 [M 86] Micro-bead Interstices Micro Mixer... 

A microfluidic system was made consisting of a Y-type channel structure and a packed bed of micro beads in a zone in the center of the outlet channel [162]. At the end of the micro-bead bed a weir is placed. The outlet channel then reopens to a larger flow zone which has several parallel micro channels, splitting the main flow into many sub-streams. These micro channels serve as spatially addressable detection lanes. 

Mixer type Micro-bead interstices mixer Width of detection lanes 50 pm... 

Inlet channel width 100 pm Micro-bead material Polystyrene... 

P 76] The micro beads were introduced into the channel by means of hand pumping in less than 30 s [162],... 

M 86] [P 76] Flow-pattern analysis without micro beads was performed to ensure that laminar-flow properties are maintained throughout the whole microfluidic system, especially concerning the weir conduit [162], Fluorescence images taken at the Y-contact, at the empty channel and at the parallel detection lanes prove that bi-... 

M 86] [P 76] The flow patterns with micro beads give a completely different fluorescence texture compared with the experiment without beads (see Flow patterns without micro-head bed, above) [162]. While the initial situation is the same, i.e. a bi-laminated structure after the Y-contact, nearly homogeneous flow patterns are found starting with the micro-bead zones and in the region of the parallel detection lanes (see Figure 1.179). Besides simple visual inspection, this is corroborated by quantitative data. The fluorescence intensity in the 10 detection lanes is virtually the same. 

Fluorescence images at the start and end of the micro-bead zone reveal that within only a short distance after entering the micro-bead bed, fluorescence is observed, whereas there is no fluorescence before [162], A quantitative fluorescence analysis confirms this visual observation. 

Figure 1.179 (a) Schematic of the microfluidic device with a zone of micro beads, (b) Optical image of the micro beds packed in the micro channel. 

Micro bead fixed to slide and moves with microscope stage... 

Fujimoto H, Mabuchi A, Tokumitsu K, Kasuh T. Irreversible capacity of lithium secondary battery using meso-carbon micro beads as anode material. J Power Sources 1995 54 440-443. 

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