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 - https://doi.org/10.1002/pssa.201700920 SN - 1862-6319 VL - 215 IS - 15 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Vahidpour, Farnoosh A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - Development of a package-sterilization process for aseptic filling machines: A numerical approach and validation for surface treatment with hydrogen peroxide JF - Sensor and Actuators A: Physical N2 - Within the present work a sterilization process by a heated gas mixture that contains hydrogen peroxide (H₂O₂) is validated by experiments and numerical modeling techniques. The operational parameters that affect the sterilization efficacy are described alongside the two modes of sterilization: gaseous and condensed H₂O₂. Measurements with a previously developed H₂O₂ gas sensor are carried out to validate the applied H₂O₂ gas concentration during sterilization. We performed microbiological tests at different H₂O₂ gas concentrations by applying an end-point method to carrier strips, which contain different inoculation loads of Geobacillus stearothermophilus spores. The analysis of the sterilization process of a pharmaceutical glass vial is performed by numerical modeling. The numerical model combines heat- and advection-diffusion mass transfer with vapor–pressure equations to predict the location of condensate formation and the concentration of H₂O₂ at the packaging surfaces by changing the gas temperature. For a sterilization process of 0.7 s, a H₂O₂ gas concentration above 4% v/v is required to reach a log-count reduction above six. The numerical results showed the location of H₂O₂ condensate formation, which decreases with increasing sterilant-gas temperature. The model can be transferred to different gas nozzle- and packaging geometries to assure the absence of H₂O₂ residues. Y1 - 2020 U6 - https://doi.org/10.1016/j.sna.2019.111691 SN - 0924-4247 VL - 303 IS - 111691 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Baltes, Klaus A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - Development of an in-line evaporation unit for the production of gas mixtures containing hydrogen peroxide – numerical modeling and experimental results JF - International Journal of Heat and Mass Transfer N2 - Hydrogen peroxide (H2O2) is a typical surface sterilization agent for packaging materials used in the pharmaceutical, food and beverage industries. We use the finite-elements method to analyze the conceptual design of an in-line thermal evaporation unit to produce a heated gas mixture of air and evaporated H2O2 solution. For the numerical model, the required phase-transition variables of pure H2O2 solution and of the aerosol mixture are acquired from vapor-liquid equilibrium (VLE) diagrams derived from vapor-pressure formulations. This work combines homogeneous single-phase turbulent flow with heat-transfer physics to describe the operation of the evaporation unit. We introduce the apparent heat-capacity concept to approximate the non-isothermal phase-transition process of the H2O2-containing aerosol. Empirical and analytical functions are defined to represent the temperature- and pressure-dependent material properties of the aqueous H2O2 solution, the aerosol and the gas mixture. To validate the numerical model, the simulation results are compared to experimental data on the heating power required to produce the gas mixture. This shows good agreement with the deviations below 10%. Experimental observations on the formation of deposits due to the evaporation of stabilized H2O2 solution fits the prediction made from simulation results. Y1 - 2019 U6 - https://doi.org/10.1016/j.ijheatmasstransfer.2019.118519 SN - 0017-9310 VL - 143 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - Sterilization of Objects, Products, and Packaging Surfaces and Their Characterization in Different Fields of Industry: The Status in 2020 JF - physica status solidi (a) applications and materials science N2 - The treatment method to deactivate viable microorganisms from objects or products is termed sterilization. There are multiple forms of sterilization, each intended to be applied for a specific target, which depends on—but not limited to—the thermal, physical, and chemical stability of that target. Herein, an overview on the currently used sterilization processes in the global market is provided. Different sterilization techniques are grouped under a category that describes the method of treatment: radiation (gamma, electron beam, X-ray, and ultraviolet), thermal (dry and moist heat), and chemical (ethylene oxide, ozone, chlorine dioxide, and hydrogen peroxide). For each sterilization process, the typical process parameters as defined by regulations and the mode of antimicrobial activity are summarized. Finally, the recommended microorganisms that are used as biological indicators to validate sterilization processes in accordance with the rules that are established by various regulatory agencies are summarized. KW - bioburdens KW - sterility tests KW - sterilization efficacy KW - sterilization methods KW - validation methods Y1 - 2021 U6 - https://doi.org/10.1002/pssa.202000732 SN - 1862-6319 N1 - Corresponding author: Michael J. Schöning VL - 218 IS - 13 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Vahidpour, Farnoosh A1 - Guthman, Eric A1 - Arreola, Julia A1 - Alghazali, Yousef H. M. A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Assessment of Various Process Parameters for Optimized Sterilization Conditions Using a Multi-Sensing Platform JF - Foods N2 - In this study, an online multi-sensing platform was engineered to simultaneously evaluate various process parameters of food package sterilization using gaseous hydrogen peroxide (H₂O₂). The platform enabled the validation of critical aseptic parameters. In parallel, one series of microbiological count reduction tests was performed using highly resistant spores of B. atrophaeus DSM 675 to act as the reference method for sterility validation. By means of the multi-sensing platform together with microbiological tests, we examined sterilization process parameters to define the most effective conditions with regards to the highest spore kill rate necessary for aseptic packaging. As these parameters are mutually associated, a correlation between different factors was elaborated. The resulting correlation indicated the need for specific conditions regarding the applied H₂O₂ gas temperature, the gas flow and concentration, the relative humidity and the exposure time. Finally, the novel multi-sensing platform together with the mobile electronic readout setup allowed for the online and on-site monitoring of the sterilization process, selecting the best conditions for sterility and, at the same time, reducing the use of the time-consuming and costly microbiological tests that are currently used in the food package industry. KW - spore kill rate KW - sterility KW - aseptic parameters KW - multi-sensing platform KW - gaseous hydrogen peroxide Y1 - 2022 U6 - https://doi.org/10.3390/foods11050660 SN - 2304-8158 N1 - This article belongs to the Special Issue "Sensors and Biosensors Application for Food Industries" VL - 11 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Abouzar, Maryam H. A1 - Poghossian, Arshak A1 - Razavi, A. A1 - Williams, O. A. A1 - Bijnens, N. A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - Characterisation of capacitive field-effect sensors with a nanocrystalline-diamond film as transducer material for multi-parameter sensing JF - Biosensors and Bioelectronics. 24 (2009), H. 5 Y1 - 2009 SN - 0956-5663 N1 - Selected Papers from the Tenth World Congress on Biosensors Shangai, China, May 14-16, 2008 ; Zeitschrift früher u.d.T. : Biosensors SP - 1298 EP - 1304 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Schöning, Michael Josef A1 - Abouzar, Maryam H. A1 - Wagner, Torsten A1 - Näther, Niko A1 - Rolka, David A1 - Yoshinobu, Tatsuo A1 - Kloock, Joachim P. A1 - Turek, Monika A1 - Ingebrandt, Sven A1 - Poghossian, Arshak T1 - A semiconductor-based field-effect platform for (bio-)chemical and physical sensors: From capacitive EIS sensors and LAPS over ISFETs to nano-scale devices T2 - MRS Proceedings Y1 - 2006 U6 - https://doi.org/10.1557/PROC-0952-F08-02 N1 - Vol. 952 - Symposium F - Integrated Nanosensors SP - 1 EP - 9 ER - TY - JOUR A1 - Bäcker, Matthias A1 - Poghossian, Arshak A1 - Abouzar, Maryam H. A1 - Wenmackers, Sylvia A1 - Janssens, Stoffel D. A1 - Haenen, Ken A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Capacitive field-effect (bio-)chemical sensors based on nanocrystalline diamond films JF - Diamond Electronics and Bioelectronics — Fundamentals to Applications III, edited by P. Bergonzo, [u.a.] Y1 - 2010 N1 - MRS Proceedings Volume 1203 paper 1203-J17-31 ; Mater. Res. Soc. Sympos. Proc. Vol 1203 (2010) ; Materials Research Society SP - 1 EP - 6 ER - TY - JOUR A1 - Poghossian, Arshak A1 - Abouzar, Maryam H. A1 - Razavi, A. A1 - Bäcker, Matthias A1 - Bijnens, N. A1 - Williams, O. A. A1 - Haenen, K. A1 - Moritz, W. A1 - Wagner, P. A1 - Schöning, Michael Josef T1 - Nanocrystalline-diamond thin films with high pH and penicillin sensitivity prepared on a capacitive Si–SiO2 structure JF - Electrochimica Acta. 54 (2009), H. 25 Y1 - 2009 SN - 0013-4686 SP - 5981 EP - 5985 ER - TY - CHAP A1 - Huck, Christina A1 - Poghossian, Arshak A1 - Bäcker, Matthias A1 - Zander, W. A1 - Schubert, J. A1 - Sukoyan, L. H. A1 - Begoyan, V. A1 - Buniatyan, V. V. A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Chemische Sensoren mit Bariumstrontiumtitanat als funktionelle Schicht zur Multiparameterdetektion T2 - 11. Dresdner Sensor-Symposium : 9.-11.12.2013 Y1 - 2013 SN - 978-3-9813484-5-3 SP - 368 EP - 372 ER -