Pyrex fabrication

We have designed, manufactured and tested a prototype that may be applied in thermal control of electronic devices. It was fabricated from a silicon substrate and a Pyrex cover, serving as both an insulator and a window through which flow patterns and boiling phenomena could be observed. A number of parallel triangular micro-channels were etched in the substrate. The heat transferred from the device was simulated by different types of electrical heaters that provided uniform and non-uniform heat fluxes, defined here respectively as constant and non-constant values... 

Xu et al. (2000) investigated de-ionized water flow in micro-channels with hy-draulie diameter ranging from 30 to 344 pm at Reynolds numbers ranging from 20 to 4,000. Two test modules were used. The first test module consisted of a cover and an aluminum plate, into which a micro-channel, inlet and outlet sumps were machined. A Plexiglas plate was used to cover the channel. The second module was fabricated from a silicon wafer, and a 5 mm thick Pyrex glass was utilized to... 

Fabrication was done by photolithography and deep reactive ion etching (DRIB). The catalyst was inserted by sputtering. Such a prepared microstructure was sealed with a Pyrex cover. The bonded micro device was placed on a heating block containing four cartridge heaters. Five thermocouples monitored temperature on the back side. A stainless-steel clamp compressed the device with graphite sheets. 

Preparation of Soluble Sample for Decarboxylation. The photolyzed fabric swatch was placed in 20 ml of distilled DMAc at 100°C for 5 minutes. The DMAc solution was filtered to remove any insoluble fibrous material from the decarboxylation flask (a round 30 ml two-neck Pyrex flask with a protruded bottom well) and dried in vacuo with the temperature kept below 50°C leaving a residual film on one side of the flask. 

Fermentation, 22, 53 Ferric nitrate, 23, 20 Fieser s solution, 21, 110 Filter fabric, Pyrex glass, 22, 33, 65 Vinyon, 22, 33, 67 Filter paper, hardened, 22, 45 Fischer indole synthesis, 22, 98 Flash distillation, 21, 85 Flask, modified Claisen, 22, 11 Fluorescence of 9-aminoacridine hydrochloride, 22, 7 Formaldehyde, 20, 60 Formalin, 22, 66 Formic acid, 20, 66, 102 23, 43 Formic acid, chloro-, benzyl ester, 23, 13... 

Nonetheless, many significant EPR studies have been accomplished with flat cells. Most commercial versions are fabricated of quartz, since Pyrex is lossy and contains paramagnetic impurities that can be detected at the high modula-... 

Micro fabrication was made by conventional silicon wet etching. Sealing was achieved by anodic bonding to Pyrex glass [67]. 

Later, Pattekar and Kothare [21] presented a silicon reactor fabricated by deep reactive ion etching (DRIE). It carried seven parallel micro channels of 400 pm depth and 1 000 pm width filled with commercial Cu/ZnO catalyst particles (from Siid-Chemie) trapped by a 20 pm filter, which also was made by DRIE, in the reactor. The reactor was covered by a Pyrex wafer applying anodic bonding. Details of the reactor are shown in Figure 2.3. 

The thermal effect is exploited to produce liquid pumping. For instance, a thermocapillary pump was constructed. The pumping method is based on surface-tension change due to local heating created by heaters fabricated on a Si-Pyrex chip. This method was used to pump reagents to perform successive PCR, gel electrophoresis, and detection [392,393],... 

Different electrode pairs were fabricated at different arms of a channel network in a Si-Pyrex chip for AC MHD pumping (see Figure 3.11). These electrode pairs allow fluid switching to occur. In AC MHD pumping, Lorentz force is used to pump electrolyte solution (e.g., 1 M NaCl). When an AC current (189 mA) flows through an electrode pair in the presence of a magnetic field (0.024 T), a flow of 0.3 mm/s is obtained [401]. 

FIGURE 5.1 The three process steps for fall-column sample stacking in a coupled column configuration fabricated on a Pyrex chip. A sample of 100 nM of FITC-Arg and FITC-Cly was used [578], Reprinted with permission from Wiley-VCH Verlag. 

In one report, a filter consisting of slits of 5- im spacings was fabricated on a Si chip. After sealing with a Pyrex glass plate, this filter was found to be able to retain latex beads of 5.78 im in diameter within a 500- im channel (see Figure 8.1) [919]. However, in the study of red blood cells (RBC) using this type of filter, the cells tended to deform and passed through the slits [835,826]. 

Microbial cells were also trapped using a 1-2 pm weir gap in a Si-Pyrex chip. This is because these cells (Cryptosporidium parvum and Giardia lamblia) contain cell walls and are not easily crushed or squeezed through the weir gap [837]. In addition, a 0.5-pm gap was fabricated in a Si-glass chip for retention of yeast cells. The gap was created by the patterned Au dots (0.5 pm high) [838],... 

Sometimes, cellular analysis was performed with cells in a flow stream, which is also termed flow cytometry or FACS in the field of cell biology. For instance, human blood cell (WBC, RBC) rheology was studied in channels fabricated on the Si-Pyrex substrates. The channels were either uncoated or coated with albumin [825]. 

The flow of leukocytes was studied in square capillaries fabricated on a Si chip, and sealed with a PDMS or Pyrex cover plate. This capillary size (cross section of 4 pm2) is similar to the diameter of a human blood capillary, but is less than both the average diameter of a leukocyte cell (10 pm) and its nucleus (6 pm). Figure 8.32 shows the difference in the flow behavior of two leukocytes (possibly neutrophils) [1175]. Deformation-induced release of ATP from erythrocytes in PDMS channels was studied. The released ATP was detected by chemiluminescence using the luciferin/luciferase system [169]. 

In another report, PCR of bacteriophage ADNA (500 bp) was performed in a 10-pL chamber fabricated in a Si-Pyrex chip. Finally, the temperature stayed at 72°C for 5 min. Subsequently, off-chip agarose gel electrophoresis was performed. Nevertheless, it was found that PCR on chip was not as efficient as conventional PCR [916]. 

---