INTRODUCTION TO PHOTOLITHOGRAPHY

To examine the nanowires by X-ray diffraction (XRD) while they are stUl embedded in the membrane, tape the membrane to a glass microscope slide with the Ni deposition side facing upward. To examine a sample of liberated nanowires, suspend the nanowires in ethanol and place a few drops on a microscope slide. After the solvent evaporates, add a few more drops and repeat this process until there is a visible pile of nanowires on the slide. Our patterns were obtained using a Scintag PADV powder X-ray diffractometer with Cu K-a radiation, a tube voltage of 40 kV and a tube current of 35 mA. 

Bisphenol-A-glycidyldimethyacrylate (Bis-GMA) 1565-94-2 2,2-dimethoxy-2-phenylacetophenone (DMPA) 24650-42-8 Oil Red O (Solvent Red 27) 1320-06-5 Oil Blue N (Solvent Blue 14) 2646-15-3 Fluorescent Yellow 3G (Solvent Yellow 98) 12671-74-8 Ethanol 64-17-5 

To prevent premature polymerization of the photoresist, store it in an amber vial or a clear vial wrapped with aluminum foil in a chemical refrigerator, if available, and minimize its exposure to light. 

Use a spatula to mass approximately 2.0 g of Bis-GMA into an amber vial. Bis-GMA is extremely viscous and sticky and you may need an additional spatula to push it to the bottom of the vial. 

If some of the Bis-GMA sticks to the sides or top of the vial, tightly screw on the vial lid and completely submerge the vial in a beaker full of hot tap water tmtil the Bis-GMA flows to the bottom. 

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These current and potential applications motivate the development of techniques for fabricating and manipulating objects with nanometer and micrometer feature sizes. This review gives a brief introduction to materials and techniques commonly used for microfabrication its focus is on those currently being explored in our laboratory. Our aim is to illustrate how non-traditional materials and methods for fabrication can yield simple, cost effective routes to microsystems, and how they can expand the capabilities of these systems. In a concluding section we provide brief descriptions of a number of other techniques for fabrication that, like those we are developing, may provide variable alternatives to photolithography. 

For a review of photolithography see Introduction to Microlithography Theory, Materials, Processes Thompson, L. F. Willson, C. G. Bowden, M. J., Eds. ACS Symposium Series 219 American Chemical Society Washington, DC, 1983. 

Chapter 1, Introduction to Liquid Microlenses, starts by describing the ubiquitous problems in optics in particular, those that can be solved by liquid microlenses. To whet the appetites of readers, we point to the benrfts and advantages of liquid microlenses in many applications for example, artificial implementation of compound eyes endoscopic fiber microscopes for confocal reflectance and real-time optical coherence tomography (OCT) photolithography optical communications orthoscopic imaging systems and labs on chips. 

Later, with the introduction of the photoresist SU-8, microstructures could be produced using the standard photolithography process, obtaining channel height of 100 pm and an aspect ratio of >10 1. Several typologies of SU-8 with different viscosities can be used to obtain different channel heights. 

An important topic of research is the introduction of the catalyst in the microreactor. In brief solid catalysts can be incorporated on the interior of micromachined reaction channels, prior to or after closure of the channel, by a variety of strategies anodic oxidation, plasma-chemical oxidation, flame combustion synthesis, sol-gel techniques, impregnation, wash coating, (electro-)plating, aerosols, brushing, chemical vapor deposition, physical vapor deposition and nanoparticle deposition or self-assembly. Some of these methods can be applied in combination with photolithography or shadow masking. 

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