Optical Micro- and Nanostructures for Applications

Knowledge of fundamental optics, sometimes combined with lessons from nature, has led to the design of micro- and nanostructures for specific applications. They may be based on reflective, refractive or diffractive effects. The most important designs are now presented. 

There are many applications where it is desirable to eliminate reflections from optical surfaces. Examples are ophthalmic or photographic lenses, mobile phone or flat panel display screens, or picture frames with a protective glass. Several approaches are known to achieve this goal, all of them involving structures on a small scale. 

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Darren J. Lipomi was bom in Rochester, New York, in 1983. He earned his BA in chemistry, with a minor in physics, from Boston University in 2005. Under Prof. James S. Panek, his research focused on the total synthesis of natural produas and asymmetric reaction methodology. He earned his AM and PhD in chemistry at Harvard University in 2008 and 2010, with Prof Geoi e M. Whitesides. At Harvard, he developed several unconventional approaches to fabricate micro- and nanostructures for electronic and optical applications. He is now an Intelligence Community Postdoctoral Fellow in the Department of Chemical Engineering at Stanford Univereity. 

Dielectrophoretic forces, though, can be induced by means other than an applied electric signal through electrodes. Optical tools can be implemented to modify an applied electric field, making these methods more susceptible for dynamic as opposed to static manipulation of electric fields with surface electrodes. Dielectrophoresis applications are not limited to particulate manipulation either. With properly configured surface-electrode geometry, it is possible to induce fluid motion and create nanoliter-sized droplets. Additionally, dielectrophoretic forces can be utilized to manipulate particles to buUd micro- and nanostructures such as wires. 

The principle and the research progress in the electrophoretic sol-gel deposition technique, which is combined sol-gel method for particle preparation and electrophoretic deposition of the sol-gel derived particles, have been described. In the principal, (1) preparation of particles by the sol-gel method, (2) deposition of particles by electrophoresis, (3) constant-voltage and constant-current deposition, and (4) solvent and electrification are introduced, hi the practical application, (1) silica thickfihns, (2) titania thick films, (3) polysilsesquioxane thick films, and (4) template-based oxide nanorods are illustrated. The electrophoretic sol-gel deposition technique offers the advantages of functional coatings in various research fields such as chemically and mechanically protective, electrically conductive, photocatalytic and bioactive materials, and it expands the possibility of fabricating optical components and ahgned micro- and nanostructures. 

Microfabrication is increasingly central to modern science and technology. Many opportunities in technology derive from the ability to fabricate new types of microstructures or to reconstitute existing structures in down-sized versions. The most obvious examples are in microelectronics. Microstructures should also provide the opportunity to study basic scientific phenomena that occur at small dimensions one example is quantum confinement observed in nanostructures [1]. Although microfabrication has its basis in microelectronics and most research in microfabrication has been focused on microelectronic devices [2], applications in other areas are rapidly emerging. These include systems for microanalysis [3-6], micro-volume reactors [7,8], combinatorial synthesis [9], micro electromechanical systems (MEMS) [10, 11], and optical components [12-14]. 

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