Glass microchips

Fernandez-Suarez, M., Wong, S. Y. F., Warrington, B. H., Synthesis of a three-member array of cycloadducts in a glass microchip under pressure driven flow. 

Kikutani, Y, Horiuchi, T., Uchiyama, K., Hisamoto, H., Tokeshi, M., Kitamori, T, Glass microchip with three-dimensional microchannel network for 2x2 parallel synthesis. Lab. Chip 2 (2002) 188-192. 

Fig. 34.5. Capillary electrophoretic system with electrochemical detection. (A) Glass microchip, (B) separation channel, (C) injection channel, (D) pipette tip for buffer reservoir, (E) pipette tip for sample reservoir, (F) pipette tip for reservoir not used, (G) Plexiglass body, (H) buffer reservoir, (I) sample reservoir, (J) blocked (unused) reservoir, (K) detection reservoir, (L) screen-printed working-electrode strip, (M) screen-printed working electrode, (N) silver ink contact, (0) insulator, (P) tape (spacer), (Q) channel outlet, (R) counter electrode, (S) reference electrode, (T) high-voltage power electrodes, (U) plastic screw. For clarity, the chip, its holder, and the screen-printed electrode strip are separated, and dimensions are not in scale. Reprinted with permission from Ref. [112]. Copyright (1999) American Chemical Society.

Guijt et al. [69] reported four-electrode capacitively coupled conductivity detection in NCE. The glass microchip consisted of a 6 cm etched channel (20 x 70 pm cross-section) with silicon nitride covered walls. Laugere et al. [70] described chip-based, contactless four-electrode conductivity detection in NCE. A 6 cm long, 70 pm wide, and 20 pm deep channel was etched on a glass substrate. Experimental results confirmed the improved characteristics of the four-electrode configuration over the classical two-electrode detection set up. Jiang et al. [71] reported a mini-electrochemical detector in NCE,... 

Zhou et al. [175] described the determination of severe acute respiratory syndrome (SARS) coronavirus by a microfluidic chip system. The unit included an LIF microfluidic chip analyzer, a glass microchip for both PCR and capillary electrophoresis, a chip thermal cycler based on dual Peltier thermoelectric elements, a reverse transcription-polymerase chain reaction (RT-PCR) SARS diagnostic kit, and a DNA electrophoretic sizing kit. According to the authors, the system allowed efficient DNA amplification of the SARS coronavirus followed by electrophoretic sizing and detection on the same chip. 

FIGURE 2.4 Electron micrograph of a T-intersection on a Pyrex glass microchip [102]. Reprinted with permission from the American Chemical Society. 

Nylon-6,6 membrane was formed at the solution interface of adipoyl chloride (0.01 M in 1,2-dichlorocthane solution) and hexamethylenediamine (0.1 M in NaOH solution) within a Pyrex glass microchip (treated with APTES) (see Figure 3.22). The membrane was used in a permeation study to examine diffusion of dissolved NH3 gas through the membrane to a phenolphthalein-containing solution [435]. The membrane can also be modified with horseradish peroxidase on only one side for carrying out an enzymatic reaction. H202 permeates through the membrane and enzymatically reacts with N-ethyl-N-(2-hydroxy-3-sulfopro-pyl)-m-toluidine and 4-AAP (4-aminoantipyrine.) to form a dye [435]. 

FIGURE 4.5 Images of sample injection at a cross-injector in a glass microchip (a) no fluorescent analyte, (b) pinched injection of rhodamine B, (c) floating injection of rhodamine B [136], Reprinted with permission from the American Chemical Society. 

Various injector geometries (simple cross, double-T, triple-T) were investigated on a glass microchip. The triple-T injector allowed for a selection of different injection volumes. For instance, a triple-T injector allowed injection of three different volumes depending on whether a cross, double-T, or triple-T configuration was used (see Figure 4.6) [529]. Pinched injection has been used consecutively to inject two samples into the same separation channel (see Figure 4.7) [557]. 

FIGURE 4.16 Image of the glass microchip used for 2D chemical separations. The separation channel for the OCEC (first dimension) extends from the first valve VI to the second valve V2. The CE (second dimension) extends from the second valve V2 to the detection point y. Reservoirs for sample (S), buffer 1 and 2 (Bl, B2), sample waste 1 and 2 (SW1, SW2), and waste (W2) are positioned at the terminals of each channel. The arrows indicate the detection points in the OCEC channel (x) and CE channel (y) [333]. Reprinted with permission from the American Chemical Society. 

FIGURE 4.21 Photograph of the glass microchip (5x2 cm) used for sample injection, separation, and interfacing into the MS system. To minimize the diffusion loss of the sample during separation, the connection between the side channels (leading from Q, R, T, U) and the serpentine separation channel (75 pm deep) was etched to 25 pm (one-ninth of the cross section area of the separation channel) [296]. Reprinted with permission from the American Chemical Society. 

To provide a stable and reproducible solid phase, the silica beads that were packed into glass microchips should be immobilized. This was achieved by using... 

FIGURE 7.14 Micrograph of a U-shaped absorption cell with an optical path length of 1000 pm on a silica glass microchip. A 250-nM fluorescein solution was used for visualization [706], Reprinted with permission from Elsevier Science. 

A glass microchip in which a cell retention chamber was bound by two barriers or weirs was constructed for cell retention (see Figure 8.8). Mouse lymphocytes were introduced into the chamber and retained in the chamber by the weirs, where the main flow of fluid passes over the weirs [1170],... 

Jurkat cells have been lysed in a flow stream in a glass microchip for cell content analysis. After cell lysis, the two preloaded fluorescent dyes and their metabolites were released from the cells and separated by CE (see Figure 8.36). To prevent cell adhesion, the glass channel surface was modified by adsorbing Pluronic F-127 to the channels. In addition, to avoid blockage of adhered cell debris and to improve migration time stability, an emulsification agent, such as Pluronic P84, was added to the separation buffer [1176],... 

In another report, PCR and subsequent CGE separation were integrated on a glass microchip (see Figure 9.1). PCR of X phage DNA was conducted in a sample reservoir with thermal cycling by a Peltier heater/cooler. Subsequent CGE separation was conducted immediately after PCR because the PCR reservoir led to the CE channel. In addition, an on-chip DNA pre-concentration device was included. This reduced the analysis time to 20 min (by decreasing the number of thermal cycles required to 10 cycles), and the starting DNA copy number to 15 (0.3 pM) [925],... 

In fabricating a glass microchip, why are drilling and bonding required ... 

Tian, H.J., Landers, J.P., Hydroxyethylcellulose as an effective polymer network for DNA analysis in uncoated glass microchips optimization and application to mutation detection via heteroduplex analysis. Anal. Biochem. 2002,309,212-223. 

Kicka, L.J., Faro, I., Heyner, S., Garside, W.T., Fitzpatrick, G., Wilding, P., Micro-machined glass-glass microchips for in vitro fertilization. Clin. Chem. 1995, 41, 1358-1359. 

Giordano, B.C., Copeland, E.R., Landers, J.P., Towards dynamic coating of glass microchip chambers for amplifying DNA via the polymerase chain reaction. Electrophoresis 2001, 22, 334—340. 

A conduction of a reaction under parallel flow in microreactor system was also demonstrated by Kitamori et al. where high conversions were achieved for phase-transfer catalyzed reactions [214]. With the use of a glass microchip, the reaction ofp-nitrobenzene diazonium tetrafluoroborate in water and in ethyl acetate took place in the aqueous layer after rapid phase transfer of 5-methylresorcinol used in excess. Not only higher yields than a conventional reaction in a flask were observed as a result of the large specific interfacial area in the microreactor but also no side products could be detected by fast removal of the main product from the aqueous to the organic phase. The separation of the two phases was easily achieved by splitting the reaction channel into two channels at the end (Figure 4.22). 

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