Surface substrate fabrication techniques

All fabrication techniques presented here are based on the use of toner from office laser printers, which is used to print a layout on a transparency film or a wax paper sheet. The transparency film is essentially used as a poly(ethylene terephthalate) (PET) substrate for polyester-toner (PT) microchannels preparation. The wax paper is used as an initial surface onto which the pattern is printed—the patterns are subsequently transferred either to a recordable compact disks (CD-R) or a glass surface. In either case, this transference is carried out with heat and pressure using the type of heat transfer machine that is used for T-shirt transfer machine or, in more sophisticated form, a tool similar to that used for hot embossing. 

Fabrication of microarrays involves deposition of nanoliter quantities of biological fluids (proteins) in a desirable arrangement of discrete spots on a substrate (e.g., glass or plastic) surface. All microarray techniques target efficient deposition of dense but uniform, homogeneous spots. There are two main types of spot formation... 

In addition to the three basic microfabrication steps discussed above, other fabrication techniques are quite useful. We will briefly discuss a few of them, namely lift-off, annealing, liquid phase photopolymerization, micromolding, soft lithography, electroplating, sacrificial processes, bonding, surface modification, laser-assisted processes, planarization, and fabrication on flexible substrates and curved surfaces. Some of these techniques do not necessarily belong to the traditional repertoire of microfabrication of ICs. However, they have proved very useful for the creation of other types of microdevices and systems such as MEMS, microfluidics, and labs on chips. 

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