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Cruz M.C.,National University of Salta | Cruz M.C.,Nanyang Technological University | Ruano G.,Bariloche Atomic Center | Wolf M.,TU Dresden | And 6 more authors.
Chemical Engineering Research and Design | Year: 2015

A novel and versatile plasma reactor was used to modify polyethersulphone commercial membranes. The equipment was applied to: (i) functionalize the membranes with low-temperature plasmas, (ii) deposit a film of poly(methyl methacrylate) (PMMA) by Plasma Enhanced Chemical Vapor Deposition (PECVD) and, (iii) deposit silver nanoparticles (SNP) by gas flow sputtering. Each modification process was performed in the same reactor consecutively, without exposure of the membranes to atmospheric air. Scanning electron microscopy and transmission electron microscopy were used to characterize the particles and modified membranes. SNP are evenly distributed on the membrane surface. Particle fixation and transport inside membranes were assessed before- and after-washing assays by X-ray photoelectron spectroscopy depth profiling analysis. PMMA addition improved SNP fixation. Plasma-treated membranes showed higher hydrophilicity. Anti-biofouling activity was successfully achieved against Gram-positive (. Enterococcus faecalis) and -negative (. Salmonella) Typhimurium bacteria. Therefore, disinfection by ultrafiltration showed substantial resistance to biofouling. The post-synthesis functionalization process developed provides a more efficient fabrication route for anti-biofouling and anti-bacterial membranes used in the water treatment field. To the best of our knowledge, this is the first report of a gas phase condensation process combined with a PECVD procedure in order to deposit SNP on commercial membranes to inhibit biofouling formation. © 2014 The Institution of Chemical Engineers.


Rupp F.,University of Tübingen | Haupt M.,Fraunhofer Institute For Grenzflachen Und Bioverfahrenstechnik | Klostermann H.,Fraunhofer Institute For Elektronenstrahl Und Plasmatechnik | Kim H.-S.,Kyung Hee University | And 10 more authors.
Acta Biomaterialia | Year: 2010

Anatase is known to decompose organic material by photocatalysis and to enhance surface wettability once irradiated by ultraviolet (UV) light. In this study, pulse magnetron-sputtered anatase thin films were investigated for their suitability with respect to specific biomedical applications, namely superhydrophilic and biofilm degrading implant surfaces. UV-induced hydrophilicity was quantified by static and dynamic contact angle analysis. Photocatalytic protein decomposition was analyzed by quartz crystal microbalance with dissipation. The surfaces were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. The radical formation on anatase, responsible for photocatalytic effects, was analyzed by electron spin resonance spectroscopy. Results have shown that the nanocrystalline anatase films, in contrast to reference titanium surfaces, were sensitive to UV irradiation and showed rapid switching towards superhydrophilicity. The observed decrease in carbon adsorbents and the increase in the fraction of surface hydroxyl groups upon UV irradiation might contribute to this hydrophilic behavior. UV irradiation of anatase pre-conditioned with albumin protein layers induces the photocatalytic decomposition of these model biofilms. The observed degradation is mainly caused by hydroxyl radicals. It is concluded that nanocrystalline anatase films offer different functions at implant interfaces, e.g. bedside hydrophilization of anatase-coated implants for improved osseointegration or the in situ decomposition of conditioning films forming the basal layer of biofilms in the oral cavity. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Hermenau M.,TU Dresden | Schubert S.,TU Dresden | Klumbies H.,TU Dresden | Fahlteich J.,Fraunhofer Institute For Elektronenstrahl Und Plasmatechnik | And 3 more authors.
Solar Energy Materials and Solar Cells | Year: 2012

In this work, we use different encapsulations to protect vacuum-evaporated small molecule organic solar cells with a simple p-i-i-stack for lifetime studies. Our devices use ZnPc and C60 as active materials. Lifetimes (T50) in a range from 300 h for un-encapsulated devices to 4000 h for glass-encapsulated have been observed. We use a model to distinguish between the water vapor transmission rate (WVTR) of the barrier and an additional WVTR of the aluminum top electrode. For all observed devices a loss of 50% of initial efficiency is observed when 10 mg m-2 water entered the device. The losses are related to a reduction of short circuit current density only, whereas open circuit voltage and fill factor remains unaffected. We relate this to an interaction of the water molecules with C60. © 2011 Elsevier B.V.


Fahland M.,Fraunhofer Institute For Elektronenstrahl Und Plasmatechnik
Galvanotechnik | Year: 2013

Plastic sheet or film is produced in vast quantities and, in various applications, is a part of everyday life. A major use is as packaging material in the foodstuffs industry. However other applications include its use in condensers. Discussed here are methods for reducing the reflectivity of such films or completely eliminating this. In certain high-end niche markets, this is a significant requirement.


The manufacture of many modern electronic devices or solar cells without using a flexible substrate such as plastic films, is almost unthinkable. Production of such devices usually involves a reel-to-reel process in which films of indium oxide and tin oxide (ITO) or zinc oxide, with thickness ranging from 10 to 100 nm are applied, using vacuum techniques. In order to prevent damage to the substrate, working pressures must not be too low nor the temperature too high. Other than ITO, combination layers based on silver have been developed whose high electrical conductivity allows thinner coatings to be used.


Fahlteich J.,Fraunhofer Institute For Elektronenstrahl Und Plasmatechnik | Fahland M.,Fraunhofer Institute For Elektronenstrahl Und Plasmatechnik | Straach S.,Fraunhofer Institute For Elektronenstrahl Und Plasmatechnik | Gunther S.,Fraunhofer Institute For Elektronenstrahl Und Plasmatechnik | Schiller N.,Fraunhofer Institute For Elektronenstrahl Und Plasmatechnik
Vakuum in Forschung und Praxis | Year: 2011

This paper reviews different vacuum based technologies for manufacturing transparent permeation barrier layers and layer stacks on flexible polymer substrates. With plasma assisted reactive evaporation, a cost-efficient, highly productive process for food packaging applications is presented. Reactive dual magnetron sputtering is a technology for the deposition of oxide layers with a very low water vapor and oxygen transmission rate at a reasonable deposition rate. Many groups suggest multilayer stacks for the encapsulation of flexible electronic devices. In this paper, an all-in-vacuum inline concept for manufacturing such multilayers is presented. It is based on the combination of reactively sputtered barrier layers with interlayers grown by using a magnetron based PECVD process (Magnetron-PECVD). Both, process parameters, such as deposition rate and process pressure, and important layer properties, such as morphology and the water vapor and oxygen transmission rate are compared for the different single and multi layer technologies. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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