Chip fabrication

Fig. 2. Digital pressure sensor on a 6 x 4.8 mm chip, fabricated at the Technical University of Berlin (5). See text.

ARROW-Chip Fabrication and Loss Characterization 18.3.1 Thin-Film Planar Fabrication and Structures... 

Substrate Patterning and Activation Strategies for DNA Chip Fabrication... 

Figure 13.1 Depiction of the glass-based lab-on-a-chip fabrication method. Shown in the figure is (a) the photoresist and chrome-coated glass substrate, (b) the coated substrate exposed to UV light through a mask (black rectangle), (c) removal of the exposed photoresist, (d) removal of the exposed chrome layer, (e) removal of glass by wet chemical etching, (f) removal of the bulk photoresist, and (g) removal of the bulk chrome layer.

FIGURE D.3 CaUper s microfluidics chip fabricated in glass. 

Chip fabrication Probes are placed on the chip by means of photolithography, pipetting, drop-touch, or piezoelectric (ink-jet). 

Use of conventional reference electrodes is a limiting factor in reducing the size of the various CHEMFETs. This could be solved by incorporating the reference electrode into the CHEMFET chip. An example of this is the on-chip fabrication of an Ag/AgCl electrode containing a gel-filled cavity sealed with a porous silicon plug [84]. Unfortunately, sensor lifetime can be limited by leakage of the reference solution. 

The focus of the present chapter is limited to review major accomplishments with partially integrated microcolumn separation systems that have been achieved in the last five years. Partial integration here refers in most cases to the fluidic part of the system which consists for example of a network of interconnected microchannels. The examples chosen have all been developed at least to the level of functional models and demonstrate principal feasibility. Many aspects of great importance in this context, such as chip fabrication, detection issues, higher levels of functional integration, etc., will be discussed in chap. 1 and 2 of this volume. 

FIGURE 3.17 Schematic illustration of Co(II) determination in a quartz chip fabricated with guide structures in the channel for multiphase flow. For details in operation, see text [428], Reprinted with permission from the American Chemical Society. 

Wang, Y., Vaidya, B., Farquar, H.D., Stryjewski, W., Hammer, R.P., McCarley, R.L., Soper, S.A., Cheng, Y.-W., Barany, F., Microarrays assembled in microfluidic chips fabricated from poly(methyl methacrylate) for the detection of low-abundant DNA mutations. Anal. Chem. 2003, 75, 1130-1140. 

Efforts continue in the Far East, particularly in Japan, by Horie et al., on photosensitive polyimides containing epoxide groups [44,45]. These studies focus on the chemical amplification of photo crosslinks in the resulting materials for use in making mask materials in silicon chip fabrication. 

Figure 10 (Top) Topographical layout of the microelectrophoresis chip fabricated in PMMA. The channels were 50 ftm in depth and varied in width (20 or 50 ftm). The injector contained a volume of 100 pL. (Bottom) SEM image of dual fiber-optic component micromachined in PMMA. (Reprinted from Ref. 68 with permisison.)...

Substrate Patterning and Activation Strategies for DNA Chip Fabrication A. del Campo I. J. Bruce... 

Nanoprinting as an Alternative Method of DNA Chip Fabrication a Case Study... 

To overcome the above mentioned problems, we developed a self-assembly DNA-conjugated polymer for novel DNA chip fabrication [66-68]. The system developed uses ssDNA as a probe and disulfide bridges located in the polymer side chain for self-assembly immobilization. This polymer can be immobilized on gold substrate with the self-assembly technique. On the surface, DNA (hydrophilic) is exposed to a solution site without lying due to the hydrophobic polymer main chain (Fig. 4). Finally, we have discriminated differential of one base mismatched sequences using DNA-conjugated polymer. 

Using PAA as the starting point, a self-assembly DNA-conjugated polymer was prepared for DNA chip fabrication. The amounts of ssDNA and PDPH in the polymer were determined by absorption measurements to be equivalent to 1/714 [molecule/monomerunit] and 1/46 [molecule/monomerunit], respectively. A 20-mer ssDNA as P-1 DNA and PDPH for self-assembled immobilization were covalently attached to PAA as side chains. After self-assembled immobilization of the DNA-conjugated polymer on the gold surface of a sensor, the P-1 DNA chain was hybridized to a 34-mer ssDNA as P-2 DNA, which had a sequence fully matched to the desired target DNA. Analysis of the first hybridization (between P-1 and P-2 DNA) and of the second hybridization (between P-2 and the target DNA) was done by fluorescence measurements. 

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