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August 1998 - present
Publications
Publications (80)
Recent advancements in photoactivated metal oxide (MOX) gas sensors and the application of plasmonic nanoparticles (NPs) in hydrogen sensing have demonstrated significant potential in enhancing sensor performance. Hydrogen, as a high‐energy, carbon‐free alternative to fossil fuels, requires reliable detection methods due to its storage and handling...
Due to the toxicity and negative environmental impact of lead‐ and chromate(IV and VI)‐based delay compositions, alternative substance mixtures are required to be investigated as possible substitutes for pyrotechnic materials. Therefore, the Mg/ CaO 2 and Mg/Li 2 O 2 delay compositions were subject of this work. These mixtures were processed into p...
Triacetone triperoxide (TATP) and Hexamethylene triperoxide diamine (HMTD), known for their propensity towards use in improvised explosive devices due to facile synthesis from readily accessible precursors, present a considerable security challenge. Their sensitivity to mechanical stimuli, such as impact and friction, as well as to thermal input, n...
In this work, the surface reactions of the homemade explosive triacetone triperoxide on tungsten oxide (WO 3 ) sensor surfaces are studied to obtain detailed information about the chemical reactions taking place. Semiconductor gas sensors based on WO 3 nanopowders are therefore produced and characterized by scanning electron microscopy, X‐ray diffr...
The following work presents algorithms for semi-automatic validation, feature extraction and ranking of time series measurements acquired from MOX gas sensors. Semi-automatic measurement validation is accomplished by extending established curve similarity algorithms with a slope-based signature calculation. Furthermore, a feature-based ranking metr...
As the identification of microorganisms becomes more significant in industry, so does the utilization of microspectroscopy and the development of effective chemometric models for data analysis and classification. Since only microorganisms cultivated under laboratory conditions can be identified, but they are exposed to a variety of stress factors,...
With the increasing demand for ultrapure water in the pharmaceutical and semiconductor industry, the need for precise measuring instruments for those applications is also growing. One critical parameter of water quality is the amount of total organic carbon (TOC). This work presents a system that uses the advantage of the increased oxidation power...
Hydrophilic surface-enhanced Raman spectroscopy (SERS) substrates were prepared by a combination of TiO2-coatings of aluminium plates through a direct titanium tetraisopropoxide (TTIP) coating and drop coated by synthesised gold nanoparticles (AuNPs). Differences between the wettability of the untreated substrates, the slowly dried Ti(OH)4 substrat...
A supramolecular approach for photonic materials based on hydrogen‐bonded cholesteric liquid crystals is presented. The modular toolbox of low‐molecular‐weight hydrogen‐bond donors and acceptors provides a simple route toward liquid crystalline materials with tailor‐made thermal and photonic properties. Initial studies reveal broad application pote...
Since thermal barrier coatings (TBCs) for turbine blades suffer from bond coat oxidation and sintering of the ceramic top coat during service, quantification of TBC degradation by non destructive evaluation methods (NDE) is essential. IN617 substrates with standard NiCoCrAlY/PYSZ EBPVD TBCs were annealed at 1100 °C and measured by impedance spectro...
Polymer fibers with liquid crystals (LCs) in the core have potential as autonomous sensors of airborne volatile organic compounds (VOCs), with a high surface-to-volume ratio enabling fast and sensitive response and an attractive non-woven textile form factor. We demonstrate their ability to continuously and quantitatively measure the concentration...
Because the robust and rapid determination of spoilage microorganisms is becoming
increasingly important in industry, the use of IR microspectroscopy, and the establishment of robust
and versatile chemometric models for data processing and classification, is gaining importance. To
further improve the chemometric models, bacterial stress responses w...
Spoilage microorganisms are of great concern for the food industry. While traditional culturing methods for spoilage microorganism detection are laborious and time-consuming, the development of early detection methods has gained a lot of interest in the last decades. In this work a rapid and non-destructive detection and discrimination method of ei...
A series of reactive binaphthyl‐diimine‐based dopants is prepared and investigated with respect to their potential for the chiral induction of structural coloration in nematic liquid crystal mixture E7 and the selective photonic sensing of nitrogen dioxide (NO2). Studies of the helical twisting power (HTP) in 4‐cyano‐4′‐pentylbiphenyl (5CB) reveal...
The simultaneous operation of multiple different semiconducting metal oxide (MOX) gas sensors is demanding for the readout circuitry. The challenge results from the strongly varying signal intensities of the various sensor types to the target gas. While some sensors change their resistance only slightly, other types can react with a resistive chang...
Surface-enhanced Raman spectroscopy (SERS) with subsequent chemometric evaluation was performed for the rapid and non-destructive differentiation of seven important meat-associated microorganisms, namely Brochothrix thermosphacta DSM 20171, Pseudomonas fluorescens DSM 4358, Salmonella enterica subsp. enterica sv. Enteritidis DSM 14221, Listeria mon...
Optical gas sensors based on chiral-nematic liquid crystals (N* LCs) forming one-dimensional photonic crystals do not require electrical energy and have a considerable potential to supplement established types of sensors. A chiral-nematic phase with tunable selective reflection is induced in a nematic host LC by adding reactive chiral dopants. The...
Explorative experiments were done to figure out differences in the emission of volatile organic compounds (VOCs) of not infested trees and trees infested by Anoplophora glabripennis (Asian longhorn beetle, ALB), a quarantine pest. Therefore, VOCs from some native insect species, Anoplophora glabripennis infested Acer, stressed Acer, healthy Acer, P...
The choice of suitable semiconducting metal oxide (MOX) gas sensors for the detection of a specific gas or gas mixture is time-consuming since the sensor’s sensitivity needs to be characterized at multiple temperatures to find its optimal operating conditions. To obtain reliable measurement results, it is very important that the power for the senso...
Bei der Bekämpfung des Asiatischen Laubholzbockkäfers (ALB) werden deutschlandweit und darüber hinaus ALB-Spürhunde eingesetzt, da eine mobile und ALB-spezifische Suche über größere Flächen bzw. in verschiedensten Suchszenarien möglich ist. Zuständig für die ALB Bekämpfung sind in der Regel die Pflanzenschutzdienste der Bundesländer, die, sofern si...
Die Kontrolle von Fracht auf Explosivstoffe durch eine Überprüfung von zuvor entnommenen Luftproben durch Spürhunde (auch bekannt als REST-Verfahren; engl.: „Remote Explosive Scent Tracing“) unterscheidet sich deutlich vom herkömmlichen Kontrollprozess mit Spürhunden. Beide Verfahren sind unter festgelegten Bedingungen auf europäischer Ebene zur Ko...
This contribution investigates the application of multiresolu-tion analysis-based pansharpening algorithms for the fusion of microscopic images generated by Raman and conventional brightfield microscopy. Using hyperspectral and panchro-matic image data of a polymer sample, eleven different established algorithms have been applied. Fusion quality as...
Discrimination and classification of eight strains related to meat spoilage and pathogenic microorganisms commonly found in poultry meat were successfully carried out using two dispersive Raman spectrometers (Microscope and Portable Fiber-Optic systems) in combination with chemometric methods. Principal components analysis (PCA) and multi-class sup...
Tagungsergebnisse des 4. Symposiums für Odorologie im Diensthundewesen an der Hochschule Bonn-Rhein-Sieg
The application of Raman and infrared (IR) microspectroscopy is leading to hyperspectral data containing complementary information concerning the molecular composition of a sample. The classification of hyperspectral data from the individual spectroscopic approaches is already state-of-the-art in several fields of research. However, more complex st...
Volatile organic compounds (VOCs) from alive Anoplophora glabripennis (ALB) imagoes, larvae and ovipositions were obtained by enrichment on adsorbents. They were analysed qualitatively by thermal desorption coupled with gas chromatography and a mass selective detector. All together 229 substances were identified: 34 from larvae, 19 from imago and 1...
Raman-Microspectroscopy with subsequent chemometric evaluation was used for the rapid and non-destructive differentiation of seven important spoilage related microorganisms, namely Brochothrix thermosphacta DSM 20171, Pseudomonas fluorescens DSM 4358, Pseudomonas fluorescens DSM 50090, Micrococcus luteus, Escherichia coli HB101, Escherichia coli TO...
This contribution investigates the application of established pansharpening algorithms for the fusion of hyperspectral images from Raman microspectroscopy and panchromatic images from conventional brightfield microscopy. Seven different methods based on multiresolution analysis and component substitution were applied and evaluated through visual as...
The freshness changes in poultry fillets during storage were studied using a portable fiber-optic Raman spectrometer. Poultry fillets with the same storage life (9 days) and expiry date were purchased from a local store and stored at 4 °C. Their Raman spectra were measured on a daily basis up to day 21 using a QE Pro-Raman spectrometer with a laser...
The study aimed to detect volatile organic compounds (VOCs) during spoilage of chicken breast filets under modified atmosphere packaging (MAP, (70% O2; 30% CO2)). Storage tests were conducted at 6 °C in a household refrigerator. Measurements were made using untreated chicken breast filets and using filets inoculated with either Pseudomonas fluoresc...
Die Detektion von Explosivstoffen stellt ein zentrales Feld der zivilen Sicherheitsforschung dar. Eine besondere Herausforderung liegt hierbei in dem Nachweis verpackter Substanzen, wie es bei Unkonventionellen Spreng- und Brandvorrichtung (USBV) häufig der Fall ist. Derzeit eingesetzte Verfahren arbeiten meist mit bildgebenden Techniken, durch die...
Tagungsergebnisse des 3. Symposiums für Odorologie im Diensthundewesen an der Hochschule Bonn-Rhein-Sieg
For mass applications like the detection of CO2 there are high demands on system costs as well as power consumption. Optical gas detection utilizing a color change effect offers a new way to fulfill these demands. However, typical CO2-sensitive substances are not optically active. In this work we present a new sensor concept based on a doped nemati...
Presentation of the Franco-German research project RE(H)STRAIN with a focus on the content of Bonn-Rhein-Sieg University of Applied Sciences and Cologne University of Applied Sciences.
Forschungsprogramme von EU und Deutschland konzentrieren sich zum Schutz kritischer Infrastrukturen sowohl auf die Prävention von Schäden als auch auf Maßnahmen zur Krisenbewältigung
Research programmes by the EU and Germany to protect critical infrastructures focus both on damage prevention and measures for crisis management
Durch Dotierung eines nematischen Flüssigkristalles mit einer chiralen Substanz wird eine helikal strukturierte Phase induziert, die in der Lage ist, einfallendes Licht wellenlängenselektiv zu reflektieren. Bei der Reaktion des Dotiermittels mit einem gasförmigen Analyten verändern sich die Ganghöhe dieser Struktur und damit die reflektierte Wellen...
In der vorliegenden Arbeit wird ein neuartiges Verfahren zur Echtzeitüberwachung von Laserbohrprozessen vorgestellt. Die Untersuchungen werden an unterschiedlichen Materialien unter Einsatz eines passiv-gütegeschalteten Nd:YAG Lasers durchgeführt. Prozessbegleitend findet eine Aufzeichnung der akustischen Emissionen mit anschließender Analyse durch...
Zusammenfassung Unkonventionelle Spreng-und Brandvorrichtungen sind Bedrohungen in den weltweiten Konfliktherden und werden bei terroristischen Aktivitäten verwendet. Der Schutz von Menschen und Material erfordert daher effektive Gegenmaßnahmen. Dazu gehört auch die Anforderung an Sicherheitskräfte oder militärisches Personal, unbekannte Substanzfu...
To test explosive properties of substances, the strong exothermal reaction of an explosive after ignition can be used. Monitoring the emitted visible or infrared radiation by photodiodes and the change in pressure by a transducer in a closed system offers a low cost and mobile explosive identification device. The explosives investigated were hexame...
EUA Annual Conference 2015
available at
http://www.eua.be/Libraries/EUA_AnnConf_2015/Poster_7_-_Bonn-Rhein-Sieg_University_of_Applied_Sciences.sflb.ashx
The temperature‐dependent sensing properties of metal‐oxide semiconductor gas sensors (MOX), based on SnO 2 and WO 3, to measure triacetone triperoxide (TATP), diacetone diperoxid (DADP), and di‐tert‐butyl‐peroxide (DTBP) and acetone are described. Conductivity measurements in the range from 100 to 400 °C operating temperature show two different re...
Many existing methods for stand-off detection of hazardous materials like IR- or Raman-Spectroscopy cannot be used if the hazardous material is concealed in a package. A robot-based laser drilling system is described as a verification detector for suspicious objects. In this reported work, semiconducting gas sensors are used for the classification...
A laser drilling system for the detection of concealed hazardous materials in objects is reported. For this task, an interdisciplinary approach is needed to combine chemical sensing technology with an embedded system for the fast analysis. In the presented work, metal oxide gas sensors are used to monitor the drilling process and material classific...
Safe Detection - Anwendungen in der Detektion von energetischen Substanzen
Lasertechniken zur Detektion von IEDs
The detection of threats is a very important task for National Security in the field of counter-terrorism. The formidable task includes development of new probes and methods for the detection of hazardous material which often is of utmost priority for security agencies. The problems related become even more complicated if a hazardous material is co...
Das Förderprojekt VESPERPLUS wird vom Bundesministerium für Bildung und Forschung im Rahmen des Sicherheitsforschungsprogramms der Bundesregierung im Themenschwerpunkt „Schutz von Verkehrsinfrastrukturen“ mit dem Gesamtziel der Erhöhung des Standards der Sicherheitsmaßnahmen im Fährverkehr gefördert. Das Forschungsprojekt ordnet sich in das übergeo...
Sensor information resulting from distributed locations and/or a multitude of instruments and heterogeneous sensors can increase the reliability of safety and security applications. Sensor nodes have been equipped with metal oxide gas sensors in order to identify hazardous materials. A number of these nodes have then been placed alongside a corrido...
Sensor information resulting from distributed locations and/or a multitude of instruments and heterogeneous sensors can increase the reliability of safety and security applications.
A gas-sensing platform was developed, communicating via a wireless sensor network based on IEEE
802.15.4 and/or Ethernet. Data from this network are aggregated via a ce...
Asymmetric threats require powerful surveillance technology which helps to preserve the security. Security checks which focus on Improvised Explosive Devices (IED’s) or the identification of persons carrying hazardous substances are the major task of our research within the HAMLeT+ (Hazardous Material Localization and Person Tracking) project. Furt...
We introduce our Lessons Learned from the NATO CNAD PoW “Defense Against Terrorism (DAT)” campaign „COMMON SHIELD” from August and September 2008, present our data and illustrate our experience, which were gathered with the experimental system HAMLeT+ (Hazardous Material Localization and Person Tracking Plus) for military camp protection. The focus...
Safety and security applications often need to gather data from distributed locations and a multitude of instruments and sensors.
We have developed a gas sensing platform that communicates via a wireless sensor network based on IEEE 802.15.4 and / or Ethernet. The data form this network is aggregated via a central server that feeds its information...
Timely recognition of threats can be significantly supported by security assistance systems that work continuously in time
and call the security personnel in case of anomalous events in the surveillance area. We describe the concept and the realization
of an indoor security assistance system for real-time decision support. The system consists of a...
Since thermal barrier coatings (TBCs) for turbine blades suffer from bond coat oxidation and sintering of the ceramic top coat during service, quantification of TBC degradation by non destructive evaluation methods (NDE) is essential. IN617 substrates with standard NiCoCrAlY/PYSZ EB-PVD TBCs were annealed at 1100°C and measured by impedance spectro...
Since thermal barrier coatings (TBCs) for turbine blades suffer from bond coat oxidation and sintering of the ceramic top coat during service, quantification of TBC degrading by non destructive evaluation methods (NDE) is essential. IN617 substrates with standard NiCoCrAlY/PYSZ EB-PVD TBCs were annealed at 1100°C and measured by impedance spectrosc...
Surface reactions of PhAs and tBAs on unoxidized and thermally oxidized GaAs(100) were studied in an UHV chamber using a differentially pumped quadrupole mass spectrometer and a molecular beam nozzle. A special sample holder allowed periodic switching between an unoxidized and an oxidized surface to observe small differences in reactivity. The foll...
