Poly microchip fabrication

R.S. Martin, A.J. Gawron, S.M. Lunte and C.S. Henry, Dual-electrode electrochemical detection for poly(dimethylsiloxane)-fabricated capillary electrophoresis microchips, Anal. Chem., 72 (2000) 3196-3202. 

Ding, Y, and Garcia, C. D., Pulsed amperometric detection with poly(dunethylsiloxane)-fabricated capillary electrophoresis microchips for the determination of EPA priority pollutants. Analyst, 131, 208, 2006. 

Martin, R.S. Gawron, A.J. Lunte, S.M. Henry, C.S. Dual Electrode Electrochemical Detection for Poly(dimethylsiloxane)-Fabricated Capillary Electrophoresis Microchips. Anal. Chem. 2000 72, 3196-3202. 

Liu, B. R, Ozaki, M., Utsumi, Y, Hattori, T, and Terabe, S. (2003). Chemiluminescence detection for a microchip capillary electrophoresis system fabricated in poly(dimethylsiloxane). Anal. Chem. 75, 36-41. 

S. M. Lunte, Carbon paste-based electrochemical detectors for microchip capillary electrophoresis/electrochemistry, Analyst, 126 (2001) 277-280. A.J. Gawron, R.S. Martin and S.M. Lunte, Fabrication and evaluation of a carbon-based dual-electrode detector for poly(dimethylsiloxane) electrophoresis chips, Electrophoresis, 22 (2001) 242-248. 

Chen, Y.H., Chen, S.H., Analysis of DNA fragments by microchip electrophoresis fabricated on poly(methyl methacrylate) substrates using a wire-imprinting method. Electrophoresis 2000, 21, 165-170. 

More recently, Sugiura et al.11 developed a fully functional microvalve based on this photoresponsive behavior, which was composed of poly(/V-isopropylacrylamide) functionalized with the chromophore spirobenzopyran (pSPNIPAAm). The microvalve was fabricated in a polydimethylsiloxane (PDMS) microchannel by in situ photopolymerization. Blue light irradiation (18 to 30 s) to the gel induced photoisomerization of the spirobenzopyran chromophore which resulted in shrinkage due to dehydration of the gel, thus causing the microvalves to open, as seen in Figure 23.7. In this example, localized irradiation enabled independent control of three photoresponsive polymer gel microvalves, which had been fabricated on a single microchip. 

A number of different polymers have been used in the production of microchip electrophoretic devices. One class of polymers is thermoplastics, which melt above a certain temperature but are hard at room temperature. Materials from this class that have been used in the formation of microchip devices include polymethylmethacrylate, polycarbonate, polyethylene, polystyrene, and a number of others. An excellent review on the fabrication and use of polymeric materials in microchips was presented by Becker and Gartner. The second class of materials is elastomeric polymers, the most widely used of which is poly(dimethylsiloxane) (PDMS). Use of this material was covered in a review by McDonald et al. ... 

An integrated poly(dimethylsiloxane), PDMS, microchip for SPE and CE followed by ESl/TOF MS has been developed and evaluated by Dahlin and coworkers [122]. The microchip (see Fig. 7) was fabricated in a two-level cross design with PDMS cast over steel wires. Following PDMS polymerization and removal of the wires, 50 pm... 

The substrate for the microfluidic device should be selected with consideration of the end application. Substrates used to fabricate the microchip device should not interact with target analytes, and must be compatible with the detection method employed (i.e., should not exhibit background fluorescence, BGF.). For the analysis of nonpolar compounds, it should be kept in mind that substrates such as poly(dimethyl)siloxane (PDMS) can adsorb hydrophobic analytes such as peptides and proteins. Plasma oxidation or treatment of the surface can sometimes be useful to minimize these interactions [34,35]. For perfusates containing organic solvents, compatibility with polymer substrates can also be an issue. Substrates to be used for the fabrication of electrophoresis-based separation devices should be capable of supporting a stable electroomostic flow (EOF). The use of a low cost material and standard processing procedures can permit mass fabrication of devices. 

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. 

Wang et al. [6] have fabricated a dualinjection electrophoretic poly(methyl methacrylate) (PMMA) microchip. It consists of two crosses on both sides of the chip and one separation channel. Anions and cations can be injected... 

In the following year, lincomycin was determined by the microchip CE-ECL system where ITO working electrode was fabricated by photolithographic method from an ITO-coated glass slide (chip substrate) located at the end of the separation channel (Fig. 5.10). The top layer made up of a poly(dimethylsiloxane) (PDMS) layer consisting of two channels, namely separation and injection channels. This microchip CE-ECL system can be successfully applied for the rapid analysis of... 

Over the past ten years, there has been an explosion of interest in the development of analytical systems in the microchip format. CE is used both to manipulate fluids and to achieve separations [4] in these devices. Very fast, highly efficient separations have been reported for such microchip CE systems. The use of CE in the microchip format allows the use of high separation field strengths (which inaeases the efficiency of the separation) because the materials typically used to construct the microchips are very efficient in dissipating heat. Most microchip CE devices have been constructed using glass [4], but devices have also been fabricated from materials such as plastics [50], low temperature co-fiied ceramics (LTCC) [51], and poly(dimethylsiloxane) (PDMS) [52]. 

Hofmann et al reported a first step toward a disposable diagnostic microchip for determination of urinary human semm albumin (HSA). They used an DEED based on a PPV derivative with a peak emission wavelength of 540 nm and which operated at drive voltages below 10 V. In a fluorescence assay, HSA was reacted with Albumin blue 580, generating a strong emission at 620 nm when excited with the OLED. Hie assay was performed in microchannels fabricated on a poly(drmethylsiloxane) microchip. HSA concentrations down to lOmgfr were detected, a limit suflicient for the determination of microalbuminuria, an increased urinary albumin excretion indicative of renal disease. 

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