P2.8.3 Adsorbent Composites Used on Mixing in Miniaturized Structures

14th International Meeting on Chemical Sensors - IMCS 2012
2012-05-20 - 2012-05-23
Nürnberg/Nuremberg, Germany
P2.8 Sensors Based on New Materials
L. Hernandez, R. Lima - Polytechnic School, University of São Paulo (Brazil), A. Leite - Institute of Physics, University of São Paulo (Brazil), E. Fachini - College of General Studies, University of Puerto Rico at Río Piedras, Puerto Rico, M. Silva - Faculty of Technology of São Paulo, CEETEPS (Brazil)
1652 - 1655


This work aims at the production, characterization and use of adsorbent plasma thin films in miniaturized structures. The films were designed to perform as passive mixers or adsorptive layers in sensors. Clustered films from tetraethoxysilane (TEOS) and nonafluoro(iso)butyl ether (HFE®) precursors on silicon, acrylic and glass substrates were prepared in an in-built plasma reactor. Profilometry and ellipsometry measurements were performed to determine thickness and refractive indexes. The chemical composition and the presence of carbon nodules were inferred from infrared (FTIR), x-ray photoelectron spectroscopy (XPS) and Raman microscopy data. Chemical characterization points out a silicone like structure, sensible to the presence of humidity as determined by CV analysis, and a fluorinated surface that protects against ultraviolet radiation (UVC). The film resistance to base/acid solutions was verified in an optical microscope. Scanning electron microscopy (SEM) revealed cluster formation in the film. Microscopic images were analyzed using ImageJ® software in order to determine cluster size and density. Contact angle measurements evaluated the hydrophobic/hydrophilic film character for volatile organic compounds (VOCs). These films present hydrophobic and organophilic characteristics; however, exposure to UVC leads to hydrophilic surfaces. The performance of miniaturized structures was simulated with FEMLAB® 3.2 software and then they were built and tested. Using a mechanical mask, 3D-microchannels were modified and used as passive mixers and/or spray formation. Thus, the results point out the utility of these films in humidity sensors or as passive layers for mixing.