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Dortmund, Germany

Mader S.,Ruhr University Bochum | Haas T.,Adlantis Dortmund GmbH | Kunze U.,Ruhr University Bochum | Doll T.,Johannes Gutenberg University Mainz
Physica Status Solidi (A) Applications and Materials Science | Year: 2011

The oxide growth on thin metal films at room temperature has been investigated in terms of resistance change during oxidation. These data have been interpreted using the extended Cabrera-Mott theory of oxidation by Boggio. The resulting oxide thickness as well as the oxidation kinetics was found to depend on pressure. According to this dependence, oxidation of ultrathin metal films can be applied for monitoring the vacuum quality inside an evacuated environment. The performance of aluminum and copper sensing layers are compared with respect to sensor lifetime and response. Furthermore, the theoretically evaluated and resistively measured oxide thicknesses are verified by TEM studies. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mader S.,Adlantis Dortmund GmbH | Mader S.,University Bochum | Haas T.,Adlantis Dortmund GmbH | Kunze U.,University Bochum | And 2 more authors.
Procedia Engineering | Year: 2010

A monitoring device for vacuum quality is realized by lowest cost single use oxygen sensors for vacuum insulation panels. They use the pressure dependence of oxide layer growth thickness on electrically measured metal nanofUms. These films were manufactured by e-beam evaporation , characterized in terms of resistance change with subsequent modeling of underlying mechanisms.

Marek P.,TU Dortmund | Marek P.,Adlantis Dortmund GmbH | Velasco-Velez J.J.,University of California at Berkeley | Haas T.,Adlantis Dortmund GmbH | And 3 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

A time-monitoring sensor based on the oxidation of leuco methylene blue (LMB) to methylene blue (MB) was developed. The sensor changes its color from yellow to green in the presence of oxygen and was integrated into a poly(vinyl alcohol) matrix. The diffusion of the oxygen in the polymer matrix as well as the oxygen uptake due to the oxidation reaction determines the time monitoring of the sensor. A physical model has been developed that accounts for both the diffusion as well as the oxidation reaction. For this purpose, the reaction kinetics was determined experimentally. Moreover, the diffusion coefficient of oxygen was determined and concentration profiles in the polymer matrix modeled. Based on these modeling, the time sensor could be calibrated very precisely. This widely applicable, low-cost visual sensor is compatible with current technologies for the processing of plastics and can be integrated into different types of packaging, e.g. for application in freshness monitoring of consumer goods. © 2012 Elsevier B.V.

Marek P.,TU Dortmund | Marek P.,Adlantis Dortmund GmbH | Velasco-Velez J.J.,Adlantis Dortmund GmbH | Haas T.,Adlantis Dortmund GmbH | And 2 more authors.
Procedia Engineering | Year: 2011

A non-electronic lifetime indicator for packaging has been developed using a colour reaction and diffusion in microchannels. It uses oxygen uptake in polymers after an originality seal is broken by manipulation or regular opening. The oxygen triggers a colour change that is made visible after desired timing period at corresponding diffusion lengths. This timing sensor was realized within a microchannel suitable for packaging cap. Rigorous design was based on modeling the diffusion - reaction equation and experimentally determined diffusion coefficients. To achieve appropriate functionality, temperature effects must be compensated using nanofunctioned materials as well as substrate diffusion of other gases like water. The methodology and design rules are generalized for microfluidics packaging. © 2011 Published by Elsevier Ltd.

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