(A) study on continuous holographic fabrication of periodic nanostructures using microfluidic device

Abstract

Recently, there have been many researches for fabrication of periodic nanostructures by various method, like self-assembly and lithography. Particularly, the lithography method has been noticed with less defects and wide range of lattices. Holographic lithography is the one of the method of lithography which uses the interference of light rather than the mask. For HL, single laser beam split into multi-beams and merge together to generated multi-dimensional interference pattern over the large area. Moreover, for simplicity of holographic lithography optical set up, single refracting prism holographic lithography was suggested. Because splitting and recombining of incoming laser beam were carried out by single refracting prism, other optical elements for controlling the angle of beams do not needed. However, with single refracting prism, it is only possible to generated one interference pattern at once. For high throughout, we suggest holographic lithography using micro prism arrays. Micro prism arrays made of transparent elastomer are molded from anisotropically etched silicon master. By the laser exposure through the micro prism arrays, it is possible to generated two- and three- dimensional hierarchical patterns of periodic structures. Besides, by controlling the distance between micro prism arrays and substrate, various shape of interference patterns are generated. Moreover, for facility of mass production, we combine micro prism arrays with micro fluidic system. A flowing stream of monomer is stopped and polymerized by holographic lithography using micro prism arrays. Then the generated structured particles are then flushed out before next polymerization is repeated. Because the structured particles have a large surface area, they have enhanced fluorescent property. With the high fluorescent signal intensity, structured particles are applicable for a variety of sensing and diagnostic fields.