TY  - JOUR
A1  - Oberländer, Jan
A1  - Mayer, Marlena
A1  - Greeff, Anton
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Spore-based biosensor to monitor the microbicidal efficacy of gaseous hydrogen peroxide sterilization processes
JF  - Biosensors and Bioelectronics
N2  - In this work, a spore-based biosensor is evaluated to monitor the microbicidal efficacy of sterilization processes applying gaseous hydrogen peroxide (H2O2). The sensor is based on interdigitated electrode structures (IDEs) that have been fabricated by means of thin-film technologies. Impedimetric measurements are applied to study the effect of sterilization process on spores of Bacillus atrophaeus. This resilient microorganism is commonly used in industry to proof the sterilization efficiency. The sensor measurements are accompanied by conventional microbiological challenge tests, as well as morphological characterizations with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sensor measurements are correlated with the microbiological test routines. In both methods, namely the sensor-based and microbiological one, a tailing effect has been observed. The results are evaluated and discussed in a three-dimensional calibration plot demonstrating the sensor's suitability to enable a rapid process decision in terms of a successfully performed sterilization.
Y1  - 2018
U6  - http://dx.doi.org/10.1016/j.bios.2017.12.045
SN  - 0956-5663
VL  - 104
SP  - 87
EP  - 94
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Jildeh, Zaid B.
A1  - Oberländer, Jan
A1  - Kirchner, Patrick
A1  - Keusgen, Michael
A1  - Wagner, Patrick H.
A1  - Schöning, Michael Josef
T1  - Experimental and Numerical Analyzes of a Sensor Based on Interdigitated Electrodes for Studying Microbiological Alterations
JF  - physica status solidi (a): applications and materials science
N2  - In this work, a cell-based biosensor to evaluate the sterilization efficacy of hydrogen peroxide vapor sterilization processes is characterized. The transducer of the biosensor is based on interdigitated gold electrodes fabricated on an inert glass substrate. Impedance spectroscopy is applied to evaluate the sensor behavior and the alteration of test microorganisms due to the sterilization process. These alterations are related to changes in relative permittivity and electrical conductivity of the bacterial spores. Sensor measurements are conducted with and without bacterial spores (Bacillus atrophaeus), as well as after an industrial sterilization protocol. Equivalent two-dimensional numerical models based on finite element method of the periodic finger structures of the interdigitated gold electrodes are designed and validated using COMSOL® Multiphysics software by the application of known dielectric properties. The validated models are used to compute the electrical properties at different sensor states (blank, loaded with spores, and after sterilization). As a final result, we will derive and tabulate the frequency-dependent electrical parameters of the spore layer using a novel model that combines experimental data with numerical optimization techniques.
Y1  - 2018
U6  - http://dx.doi.org/10.1002/pssa.201700920
SN  - 1862-6319
VL  - 215
IS  - 15
PB  - Wiley-VCH
CY  - Weinheim
ER  -