Fabrication of microfluidic separator devices via soft lithography process & developing antibacterial glass based on mn and v oxide coating

Abstract

This thesis work summarizes two separate studies carried out over a two-year period. The first project involved the development of antimicrobial glass based on Mn and V oxide coatings, performed in conjunction with Corning Incorporated. The catalytic formation of reactive oxygen species (ROS) by the two transition metal oxide (TMO) catalysts was assessed to determine the viability of developing antimicrobial products. δ-MnO2 and V2O5 were synthesized and analyzed with several spectroscopic techniques to detect and quantify the formation of two characteristic ROS: superoxide and hydrogen peroxide. δ-MnO2 was reacted with a superoxide-specific indicator molecule and analyzed with UV-Vis spectroscopy to detect an oxidation product indicative of superoxide formation. V2O5 was synthesized with a wet impregnation procedure on nanoparticle substrates and was characterized with Raman spectroscopy to ensure its stoichiometry. V2O5 was paired with a combination of H2O2-specific indicator species that fluoresced in the presence of H2O2, which were qualitatively and quantitatively analyzed by photoluminescence. δ-MnO2 did not display superoxide formation in line with literature expectations in either the thin film or powder forms. Alternatively, V2O5 produced appreciable quantities of H2O2, on the order of 1E-2 to 1E-3 μM per mg of catalyst in the dark, which are supported in the literature to prevent microbial growth. Further investigation into the catalytic activity of V2O5 when optimizing for optical conditions like transparency should be performed to assess the applicability for common applications, like smart device screens. Thicker, more opaque coats are applicable for optically-irrelevant applications, like medical surfaces and anti-biofilm coatings.In the second project, a manufacturing procedure for fabricating custom microfluidic separator devices with 100 μm features was developed using a poly(dimethylsiloxane) (PDMS) soft lithography technique. The fabricated devices are intended to utilize customizable maze-like designs to separate particle mixtures by size. The methodology was developed to purposefully avoid using specialized equipment, increasing the applicability of the procedure to pedagogical settings. Device designs were printed on cellulose acetate transparencies that were used as contact masks to image desired features on DuPontTM Riston® GoldMaster GM120 dry film photoresist that was adhered to a glass microscope slide. Exposure and development of the resist formed a “master” mold, upon which Sylgard® 184 Silicone formulation was poured and cured to form an elastomeric replica containing microfluidic channels. The cured elastomer was removed and adhered to another microscope slide to form a functional microfluidic device of custom design. The devices fabricated for the present thesis were capable of guiding particle-containing fluid through channels and complicated maze-like geometry with Re = 0.256 experimentally determined for a particular trial. Optimizing the manufacturing procedure to further decrease feature size and increase resist thickness are logical improvements to the process to be introduced in future trials. Additionally, obtaining separation behavior consistent with simulation results is of utmost importance to ensure relevance of the project.