Porous filter with spatially graded response
K.M. Krause, M. Hawkeye and M. Brett
University of Alberta, CA
glad, nanocolumn, rugate, filter, porous, optical, sensor, microfluidic
Glancing Angle Deposition (GLAD) has become a common technique for producing thin porous films with various structural features. In the current work, we have further modified GLAD in order to create porous structures that have spatially graded profiles, suitable for application in fluidic and sensor devices. During the single-step GLAD process, macroscopic shadowing was used to produce a film with thickness variation across its length. Conventional GLAD substrate motion is used, but at the centre of the substrate holder a large shadowing cylinder is placed. During deposition, a shadow is cast on the substrate. To illustrate the usefulness of this shadowing property, a spatially graded optical rugate interference stop-band filter, with defect-induced transmission peak, was grown using the macroscopic GLAD shadowing method. The rugate filter produced had a graded refractive index periodicity across its length. This resulted in a transmittance spectrum and a transmittance peak location that changed across the length of the substrate. We have fabricated a porous filter with spatially graded response which allows impregnation of optically active materials, liquids, and gases in order to provide a sensor device with advanced or specialized capabilities. Spatially graded micro-fluidic or microchromatograph devices are also possible.
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Nanotech 2007 Conference Program Abstract