Fused microfluidic chip

The interfacing of the microfluidic chip to MS was accomplished with the aid of a 10mm long fused silica capillary that was inserted in the chip and that acted as an ESI emitter. At the edge of the chip, both substrate and cover plates... 

CEC colvunns can be categorized with respect to the type of stationary phase as OT columns, packed columns, and monolithic columns, as illustrated in Figure 3. It should be noted that a particular CEC stationary phase type can be realized in a fused silica capillary, or in a channel of a microfluidic chip. 

Microreactor systems have since evolved from basic, single-step chemical reactions to more complicated multistep processes. Beider et al. (2006) claim to have made the first example of a microreactor that integrated synthesis, separation, and analysis on a single device [15]. The microfluidic chip fabricated from fused silica (as seen in Figure 1.4) was used to apply microchip electrophoresis to test the enantioselective biocatalysts that were created. The authors reported a separation of enantiomers within 90 s, highlighting the high throughput of such devices. 

Experimental Setup and Equipment The enzymatic reaction is performed in microfluidic chips from Micronit (Enschede, The Netherlands) in an etched channel with 90 pm width, 40 pm depth (isotropic etching), and a total channel volume of 3.5 pi. The chip was placed in a PEEK chip holder. Harvard Apparatus Pico Plus 11 syringe pumps (Holliston, MA) were used to supply the chip with fluids. The reaction mixture leaves the chip through a single fused silica capillary with an internal volume of 0.2 pi. 

As glass and quartz exhibit the same surface property as fused-silica capillary, the monolithic materials could be conveniently prepared in a glass- or quartz-based microfluidic device via the same way of monoliths in the capillary. However, glass/quartz devices are rather expensive, and the need for specialized facilities for their fabrication with conventional photolithography technology hinders any rapid modification of the chip architecture. An attractive alternative is using a variety of polymeric materials, such as poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA), polycarbonate (PC), and cyclic olefin copolymer (COC), to fabricate microchips for their mechanical and chemical properties, low cost, ease of fabrication, and high flexibility. 

In 2004, Hisamoto and coworkers [19] have presented a simple approach, called capillary-assembled microchips (CAs-CHIP), for assembling a commercial square fused-silica capillaiy into a PDMS microfluidic device. The capUlaiy could be completely functionalized off-chip and cut into required size and then integrated raito a chip without any solution leakage (as shown in Fig. 3). As many methods for surface modification of capillary have been well established, the CAs-CHIP method offered a way to fabricate different microfluidic devices having various functions for analytical applications including sample pretreatment, biochemical sensors, and so on. 

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