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- 8 Zerstörungsfreie Prüfung (73)
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Eingeladener Vortrag
- nein (40)
Spuren leicht flüchtiger organischer Verbindungen mikrobiellen Ursprungs (MVOC) in der Luft von Innenräumen können das Vorhandensein von Schimmelpilzen indizieren. Die Anwendung der Ionenmobilitätsspektrometrie (IMS) zur Detektion von leicht flüchtigen schimmelpilzspezifischenVerbindungen ist wegen ihrer hohen Empfindlichkeit viel versprechend. Um dieses analytisch-chemische Verfahren für eine Innenraumdiagnostik zu nutzen, wurde ein mobil einsetzbares Gerät zur Vor-Ort-Detektion getestet. Im ersten Teil der Arbeit wurden MVOC-Prüfgase im Labor generiert. Die Prüfgase wurden durch permeative Beimengungen in einen definierten Gasstrom hergestellt. Anhand dieser Prüfgase wurden die typischen IMS-Parameter, wie reduzierte Mobilität (K0), relative Driftzeit (trd), Konzentrationsabhängigkeit der Signale und daraus resultierend die Nachweisgrenze des Ionenmobilitätsspektrometer ermittelt. Die bestimmten Nachweisgrenzen der 14 untersuchten MVOC liegen im Bereich zwischen 2 und 192 μg m-3 (1 bis 51 ppbV). Im zweiten Teil wurden sieben oft im Innenraum nachgewiesene Schimmelpilzarten auf Nährmedien kultiviert und ihre produzierten MVOC detektiert. Dabei wurde festgestellt, dass Schimmelpilze art- und altersabhängige MVOC-Emissionen aufweisen. Eine statistische Auswertung und Bestätigung zeigte die Anwendung der Hauptkomponentenanalyse (PCA). Versuchsbegleitend erfolgte eine Identifizierung der MVOC durch gaschromatographische Analysen und bestätigte die IMS-Ergebnisse. Beim Schimmelpilzwachstum einer Mischsporenkultur auf drei verschiedenen Baumaterialien wurden die produzierten MVOC detektiert. Die IMS-Spektren wurden chemometrisch durch eine PCA ausgewertet. Es können die Spektren von unbeimpften und mit Schimmelpilzkulturen beimpften Baumaterialien damit unterscheiden werden ohne die stoffliche Zusammensetzung der Emissionskammerluft zu kennen. Im letzten Teil dieser Arbeit wurde das IMS in 27 Feldversuchen eingesetzt, um MVOC und damit ein Schimmelpilzwachstum in Innenräumen zu detektieren. In 59 % der Fälle wurde eine positive Korrelation zwischen einem sichtbaren Schimmelpilzbefall und den mittels IMS detektierten MVOC ermittelt.
Es wird ein Sensorsystem (HUMItrace III) zur Spurenfeuchtebestimmung in der Prozessmesstechnik vorgestellt. Die Bestimmung der Spurenfeuchte erfolgt mit neuentwickelten planaren Sensoren (HUMItrace-Sensoren) nach dem coulometrischen Messprinzip im Frostpunkttemperaturbereich von -80 °C bis -30 °C mit der Kalibriereinrichtung THG11 durch Mischen von trockenen und befeuchteten Teilgasströmen kalibriert. Die Gasfeuchte von Luft kann in diesem Bereich mit den HUMItrace-Sensoren mit einer erweiterten Unsicherheit von 2 K bestimmt werden. Die Sensoren können aber auch zur Gasfeuchtemessung in Wasserstoff, Stickstoff und Distickstoffmonoxid eingesetzt werden. Eine weitere Kalibriereinrichtung, THG-P12, generiert Prüfgase nach der Permeationsmethode; sie kann in das HUMItrace III Sensorsystem implementiert und zur vor-Ort-Kalibrierung der HUMItrace-Sensoren nach dem Standardadditionsverfahren genutzt werden.
A new planar sensor element for continuous coulometric trace humidity measurements in industrial gases has been developed. In order to ensure precise measurements a calibration facility including a precision dew point hygrometer as a reference device was developed. The sensor can measure the humidity in the frost point temperature range of -20 °C to -80 °C and has an expanded uncertainty of 2 K, a fast reaction time and a settling time of the entire system from 15 to 30 min.
Detektion von Schimmelpilzen
(2008)
Detection of microbial volatile organic compounds (MVOC) with ion mobility spectrometry (IMS)
(2009)
Spices have an important impact on daily aliment. Changes of their quality resulting in far reaching consequences in different foodstuffs and imply financial losing and even health hazard. In this study it is demonstrated that application of two different portable multi gas sensors (electronic nose and ion mobility spectrometer) supported by multivariate data analysis can contribute to ensure quality control of spice mixtures and to find out product adulteration. Headspace above spice mixtures for sausages and saveloy and product counterfeitings was investigated by a metal oxide based electronic nose (e-nose of KAMINA-type). Linear discriminant analysis (LDA) of sensor resistivity data was performed for differentiation. Simultaneously an ion mobility spectrometer (IMS) was coupled to the emission chamber for detection of gaseous components above spice mixtures. The measured spectra show differences between the two spice mixtures and were discussed using a principal component analysis (PCA). The two multigas sensors permit discrimination between the types of spice mixtures and can indicate product adulteration. Additionally, a headspace gas analysis by gas chromatography was performed to identify the main volatile components and to prove the chemical basis for the observed differences of the multi gas sensors.
This work focuses on the design and fabrication of low-cost and fast-response of an electronic nose (E-nose) based on semiconductor gas sensors, for discriminating some synthetic gases such as ammonia (NH3), ethanol (C2H5OH), and hydrogen sulfide (H2S). Additionally, the capability of separating different concentration levels of each considered gases was checked. Dataset treatment of E-nose by using Principal Component Analysis (PCA) showed a good discrimination of the different synthetic gases. Furthermore, perfect classification was reached of different concentration levels of the analysed gases by using Discriminant Function Analysis (DFA). In the light of these results, it could be stated that the developed E-nose system constitutes an inexpensive, rapid, simple to use, and efficient tool for synthetic gases detection.
Ein Umlaufkühler ist im Betrieb explodiert. Splitter des zerborstenen Gehäuses aus Kunststoff wurden mit dem Kühlwasser in die Umgebung geschleudert, am Betriebsort entstand Personenschaden. Bei Funktionsprüfungen am beschädigten Gerät traten unerwartet - aber reproduzierbar - Knalleffekte bei Berührung der Außenoberfläche der Kupfer-Kühlschlange auf. Ein möglicher Mechanismus konnte im Labor durch Synthese von Kupferazid auf Kupferproben und Auslösung vergleichbarer Knalleffekte nachgestellt werden. Damit ist die Plausibilität des beschriebenen Schadensereignisses mit diesem oder einem ähnlich reagierenden Stoff belegt. Ein eindeutiger Nachweis darüber, dass bei dem aufgetretenen Schadensfall dieselbe chemische Reaktion stattgefunden hat, war nicht möglich, da die Belag-Überreste aus dem explodierten Kühlgerät für eine Analyse nicht mehr in ausreichender Menge verfügbar gewesen sind.
Monitoring of repositories for radioactive waste requires techniques which can be applied long-term under harsh conditions. In this work, the reliability and suitability of materials and a capacitive sensor for measuring relative humidity are investigated, which are to be embedded in the special concrete components for the closure structures of underground repository. Preliminary tests with accelerated aging of the materials used, validation of the sensors under difficult conditions, investigations of the surfaces after aging by pH 14 solution, defined exposure of the sensors in a climatic chamber and the microscope images are discussed. The results will be used for further development and optimization of the RFID based sensor systems which can be applied to monitor the condition of different building structures without cabling.
In this study, the ability of an electronic nose developed to analyze and monitor odor emissions from three poultry farms located in Meknes (Morocco) and Berlin (Germany) was evaluated. Indeed, the potentiality of the electronic nose (e-nose) to differentiate the concentration fractions of hydrogen sulfide, ammonia, and ethanol was investigated. Furthermore, the impact change of relative humidity values (from 15% to 67%) on the responses of the gas sensors was reported and revealed that the effect remained less than 0.6%. Furthermore, the relevant results confirmed that the developed e-nose system was able to perfectly classify and monitor the odorous air of poultry farms.
In this work, we demonstrate the ability of an electronic nose system based on an array of six-semiconductor gas sensors for outdoor air quality monitoring over a day at a traffic road in downtown of Meknes city (Morocco). The response of the sensor array reaches its maximum in the evening of the investigated day which may due to high vehicular traffic or/and human habits resulting in elevated concentrations of pollutants. Dataset treatment by Principal Component Analysis and Discriminant Function Analysis shows a good discrimination between samples collected at different times of the day. Moreover, Support Vector Machines were used and reached a classification success rate of 97.5 %. Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC-MS) technique was used to validate the developed e-nose system by identifying the composition of the analyzed air samples. The discrimination obtained by e-nose system was in good agreement with the TD-GC-MS results. This study demonstrates the usefulness of TD-GC-MS and e-nose, providing high accuracy in discriminating outdoor air samples collected at different times. This demonstrates the potential of using the e-nose as a rapid, easy to use and inexpensive environmental monitoring system.
Sensor systems are widely used in hydrogen technologies. The lecture presents requirements and properties of sensor systems and shows application examples of these technologies for safety and process control for hydrogen technologies. The focus is on gas sensors as well as sensors for pressure, temperature and gas flow. These systems are applied, among other things, for monitoring and control of operating conditions, indication of hazardous conditions and triggering of alarms.
The determination of the measurement uncertainty of quantitative and qualitative results is an important quality management tool, for example to describe measuring equipment, procedures, measurement results and the quality of products. The lecture presents the process description for the determination of the measurement uncertainty according to GUM, the determination of uncertainties in qualitative measurement results and the application of the measurement uncertainty for conformity assessment.
Introduction of H2Safety@BAM
(2021)
This contribution for the Open Forum of the 8th HSN Symposium introduces the SensRef activities of the Competence Centre H2Safety@BAM.
The evaluation of measurement uncertainty is essential for testing and calibration laboratories. This paper provides a general process description for the determination of the measurement uncertainty of quantitative data and its application to the conformity assessment with examples, and how to deal with the uncertainty of qualitative (Boolean) results, e. g. when "Alarm" or "No alarm" occours in an instrument display.
The internal project "SealWasteSafe" of the Federal Institute for Materials Research and Testing is dedicated to the further improvement in the construction of sealing systems for underground repositories of radioactive waste. Particularly, a multi-sensory concept is developed to ensure quality assurance and continuous long-term monitoring on the engineered barriers. Therefore, beside other measures, the temperature and equilibrium moisture of the construction shall be monitored and respective multi-sensoric monitoring concepts are tested first on the laboratory scale. One focus in this project is on embedded application in alkali-activated mortars (AAM), which results in special requirements for the resistance of the sensors to strongly alkaline environments with up to pH 14. In addition, the ingress of water along cables or at sensor positions is critical for sensors embedded in concrete, as the cable access of the sensor housing is a major weak point. It is therefore advisable to equip wireless high frequent radio frequency identification-based sensors, so called HF RFID sensors (short: RFID), that do not require cable access and thus have a stable and leak-proof sensor housing for long-term monitoring. In this contribution, the results from temperature, moisture and transmitted power monitoring of a AAM and a M2 specimens by means of HF RFID sensor systems are presented.
In the present paper the development of a semi-automated device for long-term monitoring of gaseous ammonia is described. A sensor material was produced that changes its optical properties in the pres-ence of low concentrations of ammonia in air. The implementation into an electronic device enables precise, simple, economic and fast monitoring of low concentrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables.
The testing of gas and humidity sensors is essential for the application of sensing devices. The testing determines properties of an investigated humidity sensor or gas sensor. In testing, the sensor property is the observed response of a sensing system to an input stimulus in comparison to a reference within a test procedure. This tutorial is structured into six chapters. The first chapter is about basics of hygrometry and gas sensing. It includes definitions, sensor classification, overview of application categories, as well as construction and functional principles. The chapter on requirements of deployed sensors focus on stability, response time, cross-sensitivity, electrical and mechanical requirements, and other. The sensing performance is characterised by determinations of parameters like accuracy, repeatability, detection limits (low and high), and response/recovery time. The description of testing signals on specified qualitative and quantitative characteristics, and the adequately estimated measurement uncertainty is the content of the analysis chapter. All chapters contain examples of testing procedures from testing/calibration labs for hygrometers and gas sensors which are essential for implementation into quality management systems.
This project addresses the application of safe and healthy workplaces in offices, chemical laboratories and other workplaces where indoor air quality plays an important role. The LoRaWAN (Long Range Wide Area Network) is used as a communication interface to make sensor data globally accessible.
The objectives of the project are to create a sensor node and an online and offline system that collects the data from the sensor nodes and stores it on a local server, in a cloud, and also locally on the node to prevent communication failures. An important point in this project is the development of the sensor nodes and the placement of these in the premises, thus no development work is involved in Building the infrastructure.
Poor air quality, particularly in urban areas, causes various diseases and degrades living standards. Air Quality could be affected by emissions of odor, Volatile Organic Compounds (VOCs), and other gases. Therefore, assessment and monitoring of odorous air quality using sensitive, simple, rapid, accurate and portable tools is very important for public health. This study aimed to characterize odor emissions to detect malfunctions in facilities and to prevent air pollution and olfactory nuisance in the environment. A gas chromatographic method, in conjunction with sensorial analysis were performed for odorous air samples analysis collected from neighborhood of Meknes city (Morocco). Advanced multivariate statistical approaches, such as Principal Components Analysis (PCA), Discriminant Function Analysis (DFA), Support Vector Machines (SVMs), and Hierarchical Cluster Analysis (HCA), were used to describe samples similarities. The electronic nose (e-nose) data processing exhibits a satisfactory discrimination between the odorous air samples. Twenty-four VOCs with known molecular formulas were identified with Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC-MS). A validated Partial Least Square (PLS) model foresees good calibration between e-nose measurement and TD-GCMS analysis. The finding indicates that TD-GC–MS approach in conjunction with e-nose unit could be suitable tool for environmental measurement-based odor emissions.
Ein Umlaufkühler ist im Betrieb explodiert. Splitter des zerborstenen Gehäuses aus Kunststoff wurden mit dem Kühlwasser in die Umgebung geschleudert, am Betriebsort entstand Personenschaden. Bei Funktionsprüfungen am beschädigten Gerät traten unerwartet - aber reproduzierbar - Knalleffekte bei Berührung der Außenoberfläche der Kupfer-Kühlschlange auf. Ein möglicher Mechanismus konnte im Labor durch Synthese von Kupferazid auf Kupferproben und Auslösung vergleichbarer Knalleffekte nachgestellt werden. Damit ist die Plausibilität des beschriebenen Schadensereignisses mit diesem oder einem ähnlich reagierenden Stoff belegt. Ein eindeutiger Nachweis darüber, dass bei dem aufgetretenen Schadensfall dieselbe chemische Reaktion stattgefunden hat, war nicht möglich, da die Belag-Überreste aus dem explodierten Kühlgerät für eine Analyse nicht mehr in ausreichender Menge verfügbar gewesen sind.
Wastewater contains harmful chemicals and heavy metals that are known to cause various environmental and health problems. Therefore, the water quality control using sensitive, simple, fast, accurate, and portable tools is of great importance. This study aimed to evaluate the pollution parameters of wastewaters collected at different treatment stages from a wastewater treatment plant (WWTP) that treats domestic and industrial wastewaters by using an electronic nose (E-nose) and a voltammetric electronic tongue (E-tongue) combined with chemometric techniques. Water and wastewater pollution parameters determination were performed using inductively coupled plasma optical emission spectrometry for the determination of cations, and anions by using ion chromatography. Chemometric techniques, such as Principal Component Analysis (PCA), Discriminant Function Analysis (DFA), Support Vector Machines (SVMs), and Hierarchical Cluster Analysis (HCA), were used to process the E-nose and E-tongue datasets to describe the similarities between the samples. In addition, Partial Least Squares Regression (PLSR) model was constructed using electronic sensing data to simultaneously predict the concentration values of physicochemical parameters. The obtained correlation coefficient, for training and testing sets, is higher than 0.91 for the prediction of the concentration of all physicochemical parameters, except for iron (Fe) which remains 0.84. These results suggest that simple, portable, and inexpensive tools such as electronic nose and tongue are suitable for wastewater analysis.
Die Optimierung und Validierung des digitalen Wasserstofftankstellenmanagements mit Sensortechnologien ist das übergeordnete Ziel des Teilprojekts Digitale Qualitätsinfrastruktur mit Sensortechnologien (QIST) am Use Case H2, im Rahmen der digitalen Qualitätsinfrastruktur (QI digital[1]). Hierfür sollen u.a. Sensornetzwerke mit digital-gestützten Auswertungsstrategien intelligent gestaltet werden (Stichwort KI bzw. digitaler Zwilling). Verschiedene, sich ergänzende Sensoren, Systemkomponenten und KI-Methoden stehen als Bausteine intelligenter Sensorsysteme zur Verfügung, mit dem Zweck, die physikalischen und chemischen Parameter an und in Anlagen umfassend und effizient zu überwachen sowie Fehlfunktionen zuverlässig zu detektieren und zu interpretieren, Abbildung 1.
Konkrete Arbeitsschritte sind, nach dem Aufbau der Versuchsplattform „Wasserstofftankstelle“, die Instrumentierung von Sensorik und deren digitale Integration in das Tankstellenmanagementsystem sowie die Validierung im Realbetrieb. Die somit erzielten Messergebisse sowie die Messunsicherheiten, Historien und Verfahren werden in digitaler Form aufbereitet, gespeichert und fortlaufend in die KI-basierte Datenauswertung einbezogen, inkl. der Anbindung an die metrologische Rückführungskette.
Ziele sind:
• Einführung eines neuen messtechnischen Ansatzes und eines digitalen Zwillings für den Anwendungsfall "Wasserstofftankstelle" auf Basis der H2-Sensorik sowie der Zustandsgrößen Druck und Temperatur
• Qualitätssicherung durch Applikationen zuverlässiger Gassensorik, Manometer und Thermometer sowie KI-Methoden zur Prozesskontrolle und Detektion von Fehlfunktionen
• Nutzung von digitalen Kalibrierscheinen (DCCs) insbesondere für die Messgröße Temperatur zur Realisierung der metrologischen Rückführung in einer digitalen Qualitätsinfrastruktur
An experimental investigation has been carried out to characterize and discriminate seven saffron samples and to verify their declared geographical origin using a voltammetric electronic tongue (VE-tongue). The ability of multivariable analysis methods such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) to classify the saffron samples according to their geographical origin have been investigated. A good discrimination has reached using PCA and HCA in the VE-tongue characterization case. Furthermore, cross validation and Partial Least Square (PLS) techniques were applied in order to build suitable management and prediction models for the determination of safranal concentration in saffron samples based on SPME-GC-MS and UV-Vis Spectrophotometry. The obtained results reveals that some relationships were established between the VE-tongue signal, SPMEGC-MS and UV-Vis spectrophotometry methods to predict safranal concentration levels in saffron samples by using the PLS model. In the light of these results, we can say that the proposed electronic system offer a fast, simple and efficient tool to recognize the declared geographical origin of the saffron samples.
A portable device for calibration of trace humidity sensors and an adopted calibration procedure have been developed. The calibration device is based on humidity generation by permeating water through polymeric membrane tubes. Water vapour transmission rates for various polymers were experimentally determined in order to select the most suitable polymeric material. The developed trace humidity generator consists of a gas-flow polymeric hose immersed in a water reservoir thermostated by a sensorcontrolled heater. Mole fractions of water vapour between 1 µmol/ molˉ¹ and 350 µmol/molˉ¹ (equivalent to frost-point temperatures from -76 °C to -31 °C) were generated by varying either the operating temperature or gas flow. The operating temperature can be varied from 20 °C to 60 °C and kept stable within 0.1 K. Uncertainty analysis indicated that the trace humidity generator produces gas flows of constant humidity amounts with a relative expanded uncertainty less than 3.4% (k = 2) of the generated value.
The Stolt Rotterdam tanker ship, filled with nitric acid, was unloading at the Krefeld-Uerdingen terminal on the Rhine River in November 2001. Nitric acid ran out of the stainless steel tanks into the ship's hull and damaged the structural steel. The ship then caught fire and sank at the terminal. Large quantities of nitrogen oxides were emitted, which drifted towards a residential area. Additionally, a mixture of acid and water was introduced into the Rhine River. The area became hazardous to people and the natural environment; however, the imminent danger for the residents and the environment was reduced because of the protective measures against pollution and the good teamwork between local authorities, fire brigades and the Bayer AG company. The acid was drained off of the ship using a controlled discharge of the acid into the river. Through the use of this measure, the ship was salvaged, limiting the pollution to the area and removing the health hazards to the people and the environment. After the ship was salvaged, the river police, along with assistance from the BAM Federal Institute for Materials Research and Testing, impounded the ship and selected corroded parts for further examination. Some of these components have been examined in detail by the BAM. These material investigations contributed to the elucidation of the origin of the leak in the floor panel. The cause of damage was deemed to be a result of a construction flaw at the enamelled valve on the load and discharge pipes.
The results from the comparative corrosion testing using the original structural steel and 60% acid revealed that the valves began to leak at least 8 h prior to the incident at the terminal.
Application of electronic nose and ion mobility spectrometer to quality control of spice mixtures
(2009)
Traces of microbial volatile organic compounds (MVOCs) in air can indicate the presence of growth of moulds in the indoor environment. Ion-mobility spectrometry is a very promising method for detection of these MVOCs, because of its high sensitivity. For development of an in-situ method for detection of MVOCs, a portable ion-mobility spectrometer (IMS) was used and test gases of 14 MVOCs and their respective mixtures were investigated. IMS spectra were recorded as a function of concentration of MVOCs in air. Drift time and mobility of reactant ions formed in positive polarity mode were determined and correlated with the mass-to-charge ratio (m/z) of the MVOCs investigated. The estimated detection limit has a specific value for each MVOC and is in the range 3 to 96 µg m-3 (1 to 52 ppbV). Indoor trials show that IMS can indicate hidden mould growth.
Detektion von leicht flüchtigen Schimmelpilzmetaboliten mittels Ionen-Mobilitäts-Spektrometrie (IMS)
(2009)
The detection of the aroma and flavour volatile compounds of spices is key in product quality control. Accordingly, it is necessary to develop new electronic sensing systems for food adulteration control and authenticity assessment for protecting customer's health.
In this work, the capability of the E-nose and VE-tongue in combination with SPME-GC-MS to correctly discriminate between several cumin samples of different geographical origins and to detect their adulteration, by using unsupervised and supervised chemometric tools, was evaluated. Regarding the aroma profile, eleven volatile compounds were characterized by SPME-GC-MS; all of them were found in cumin powder while only eight are found in cumin seeds. The main volatile compounds detected were b-pinene, m-cymene, g-terpinene, cuminaldehyde and cuminic alcohol, in different proportions depending on the cumin sample form (seed or powder). In summary, the results obtained are sufficiently encouraging as a starting point for the development of new electronic sensing systems with more improvement in the reliability of the sensor's performance as well as chemometric tools in order to deal with a complex dataset.
A metrological approach to improve accuracy and reliability of ammonia measurements in ambient air
(2016)
The environmental impacts of ammonia (NH3) in ambient air have become more evident in the recent decades, leading to intensifying research in this field. A number of novel analytical techniques and monitoring instruments have been developed, and the quality and availability of reference gas mixtures used for the calibration of measuring instruments has also increased significantly. However, recent inter-comparison measurements show significant discrepancies, indicating that the majority of the newly developed devices and reference materials require further thorough validation. There is a clear need for more intensive metrological research focusing on quality assurance, intercomparability and validations. MetNH3 (Metrology for ammonia in ambient air) is a three-year project within the framework of the European Metrology Research Programme (EMRP), which aims to bring metrological traceability to ambient ammonia measurements in the 0.5–500 nmol mol−1 amount fraction range. This is addressed by working in three areas: (1) improving accuracy and stability of static and dynamic reference gas mixtures, (2) developing an optical transfer standard and (3) establishing the link between high-accuracy metrological standards and field measurements. In this article we describe the concept, aims and first results of the project.
Ionische Flüssigkeiten als neuartige Sensorbeschichtung für coulometrische Spurenfeuchtesensoren
(2018)
Die Arbeit präsentiert erste Messungen mit coulometrischen Sensoren, die mit einer ionischen Flüssigkeit beschichtet sind. Diese Sensoren werden in der Industrie verwendet, um die Spurenfeuchte in unterschiedlichen Gasen zu messen. Normalerweise erfolgt eine Beschichtung der Sensoren mit Phosphorpentoxid und dessen Hydrolyseprodukte. In dieser Arbeit wurde stattdessen eine hygroskopische ionische Flüssigkeit benutzt. Die generierte Gasfeuchte für die Untersuchungen betrug bezogen auf die Frostpunkttemperatur -80 °C bis -30 °C, was gleichbedeutend mit einem Wasserdampf-Stoffmengenanteil von 0,5 μmol·mol-1 bis 376 μmol·mol-1 ist. Zusätzlich zu der Messung mit coulometrischen Sensoren erfolgte eine Referenzmessung der Gasfeuchte mittels eines Taupunkthygrometers. Erste Ergebnisse haben gezeigt, dass es möglich ist mit dieser Art der Beschichtung unterschiedliche Gasfeuchten zu messen. Aber es ergaben sich trotz gleicher Feuchte unterschiedliche Signalintensitäten bei den benutzen Sensoren und es zeigte sich eine Drift des Sensorsignales.
Technische Richtlinien enthalten Empfehlungen sowie Anforderungen zum Stand der Technik zur Aufstellung von Bewertungskriterien und Behandlung wissenschaftlich-technischer Fragen. Sie fördern den Erfahrungsaustausch und Technologietransfer zwischen Entwicklern und Anwendern.
In unserem Beitrag stellen wir die Richtlinie VDI/VDE 3518 vor. Diese Richtlinienreihe definiert Begriffe, beschreibt den Aufbau und klassifiziert Multigassensoren (Blatt 1), befasst sich mit den Anforderungen für das Unterscheiden, Erkennen und mengenmäßige Bestimmen von Gemischen gasförmiger Stoffe und die Prüfung von Multigassensoren (Blatt 2) und gibt Anleitung für geruchsbezogene Messungen mit „Elektronischen Nasen“ (Blatt 3). Multigassensoren können als elektronische Nasen in Anlehnung an den biologischen Geruchssinn zur Wahrnehmung und Charakterisierung von Gerüchen eingesetzt werden. Die Spezifik von Multigassensoren besteht darin, dass durch die Wahl und Betriebsweise der Sensoren eine Vielzahl von geeigneten Messsignalen erzeugt werden, aus denen mit mathematischen Verfahren die für die Anwendung gewünschten Informationen extrahiert werden. Dazu ist ein Training der Messeinrichtung mit Proben bekannter Eigenschaften notwendig.
Diese Richtlinie soll Herstellern, Anbietern und Nutzern als ein Leitfaden Informationen und Erläuterungen für die korrekte und sichere Arbeit mit Multigassensoren liefern. Sie soll Prüflaboratorien und Anwendern helfen, bei der Beurteilung von Qualitätsmerkmalen einheitlich vorzugehen und dafür gemeinsame Randbedingungen anzugeben
Leaking methane (CH4) from infrastructures, such as pipelines and landfills, is critical for the environment but can also pose a safety risk. To enable a fast detection and localization of these kind of leaks, we developed a novel robotic platform for aerial remote gas sensing. Spectroscopic measurement methods for remote sensing of selected gases lend themselves for use on mini-copters, which offer a number of advantages for inspection and surveillance over traditional methods. No direct contact with the target gas is needed and thus the influence of the aerial platform on the measured gas plume can be kept to a minimum. This allows to overcome one of the major issues with gas-sensitive mini-copters. On the other hand, remote gas sensors, most prominently Tunable Diode Laser Absorption Spectroscopy (TDLAS) sensors have been too bulky given the payload and energy restrictions of mini-copters. Here, we present the Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS), which combines a novel lightweight TDLAS sensor with a 3-axis aerial stabilization gimbal for aiming on a versatile hexacopter. The proposed system can be deployed in scenarios that cannot be addressed by currently available robots and thus constitutes a significant step forward for the field of Mobile Robot Olfaction (MRO). It enables tomographic reconstruction of gas plumes and a localization of gas sources. We also present first results showing its performance under realistic conditions.
Pollution through emission of toxic gases is an increasing problem for the environment. It affects similarly agricultural, industrial and urban areas. In future, environmental emissions in ambient air must be monitored at even lower concentrations as nowadays. One environmental relevant compound is ammonia and its conversion product ammonium that have strong negative impact on human health and ecosystems. Most ammonia measurements in ambient air are performed in the range below 1000 nmol·mol 1 and thus there is a need for reliable traceable ammonia gas standards and in addition in situ analytical procedures for monitoring (in ambient air to avoid that thresholds are exceeded). Therefore, the use of reference materials is necessary for development accompanying test or for calibration, e. g. of structure-integrated sensors and mobile multi-gas sensors.
The developed gas standard generator produces gas mixtures that comply with the metrological traceability for ammonia gas standards in the desired environmentally relevant measurement range. The method is based on the permeation of ammonia through a membrane at constant temperature and pressure. The resulting ammonia penetrant gas flow is then mixed with a carrier gas flow to generate a gas standard flow of known concentration. The dynamic rage is enlarged by using a two dilution steps. Depending on the permeation rate, generable molar fractions are possible in the range nmol·mol-1 to a few µmol·mol-1. We present the design of an ammonia gas standard generator and first results of the characterisation of its individual components supporting the uncertainty assessment according to GUM for stable gas concentrations in this range. The relative uncertainty of the generated ammonia gas standard is smaller than 4 % (k = 2).
Im Projekt KonSens werden für die Anwendungsbei-
spiele bauteilintegrierte Sensorik für Betonkomponen-
ten und mobile Multigassensorik Sensorsysteme in
Form von Funktionsmustern entwickelt, validiert und
angewendet. Schwerpunkte liegen einerseits in der
Detektion und Bewertung von Korrosionsprozessen in
Beton und andererseits in der Detektion und Quantifi-
zierung sehr geringer Konzentrationen toxischer Gase
in der Luft. Dabei ist die Adaption der sensorischen
Methoden aus dem Labor in reale Messumgebungen
inklusive geeigneter Kommunikationstechnik ein
wichtiger Aspekt.
Innovation is the catalyst for the technology of the future. It is important to develop new and better technologies that can continuously monitor the environmental impact, e.g., for air Quality control or emission detection. In the recently at BAM developed Universal Pump Sensor Control (UPSC3) module, different components and sensors are fused. The combination of the individual components makes the UPSC3 module an excellent monitoring and reference system for the development and characterization of gas specific sensors. Measurements over long periods are possible, for mixed gas loads or for certain gas measurements. The System is part of a mobile sensor network of several sensor units, which can also be used as standalone systems.
This work presents a first attempt to use ionic liquids as a new coating for planar coulometric sensors. These sensors are used for the measurement of trace humidity in various gases. Usually, the coating of the sensors is tetraphosphorus decaoxide and its hydrolysis products. Instead, a hygroscopic ionic liquid was used as sensor coating in this work. Generated frost point temperatures tf in the gas ranged from -80 °C to -30 °C, which is equivalent to vapour mole fractions xv from 0.5 μmol·mol-1 to 376 μmol·mol-1. In addition to the coulometric sensors, the generated humidity is determined by a precision dew point hygrometer as reference. First results show that it is possible to measure humidity with ionic liquid based coulometric sensors.
Planar coulometric sensors were investigated in humidified synthetic air at various absolute gas pressures, i. e. 2 bar, 5, bar, 10 bar, and 15 bar. Humidified gas flow at adjusted gas pressure was split into two flows, one passed a coulometric sensor and the other one passed a reference hygrometer after decompression. Both signals were recorded and then compared after calculation of resulting frost point temperature. Calculation is based on a calibration function obtained at ambient pressure. Comparison showed that an increasing pressure resulted in a higher derivation between sensor signal (calculated frost point temperature) and reference frost point temperature. At an absolute pressure of 2 bar the differences were minor in consideration of the uncertainty, however at 15 bar the differences were 6.77 K. Nevertheless, it was possible to measure the gas humidity at higher pressure with coulometric trace humidity sensors.
Die Varroose gilt weltweit als eine der bedeutendsten Erkrankungen der westlichen Honigbiene, Apis mellifera. Verursacht wird sie durch den Ektoparasiten Varroa destructor, der durch Saugen der Hämolymphe und Virenübertragung sowohl die Bienenbrut als auch die adulten Individuen schädigt.
Ohne imkerliche Unterstützung gehen betroffene Bienenvölker in der Regel innerhalb von drei Jahren ein. Als bewährte, häufige Behandlung wird flächendeckend 60%ige Ameisensäure (AS) -im Bienenstock appliziert über verschiedene Verdampfungssysteme- eingesetzt. Sie wirkt als einziger zugelassener Wirkstoff gegen die Varroamilbe auch in die verdeckelte Brut hinein und birgt kein Risiko der Resistenzentwicklung.
Allerdings ist das therapeutische Fenster, der Bereich zwischen Milbenabtötung und Bienenschädigung, relativ schmal und die tatsächliche AS-Konzentration im Bienenstock stark abhängig von äußeren Einflussfaktoren, wie Temperatur oder Applikationsart.
Eine Bestimmung der exakten AS-Konzentration im Bienenstock ist also notwendig, um einerseits das Wirkungsoptimum zu bestimmen und andererseits bei Übersteigen der Maximalkonzentrationen mit Folge-Schädigung der Bienen, ein rechtzeitiges Eingreifen der Imker zu ermöglichen.
Die Entwicklung eines Detektors zur Bestimmung der tatsächlichen AS-Konzentration in der Bienenstockluft würde einen großen Fortschritt in den Bereichen der Bienenforschung, der Varroa-Behandlung in der Imkerei, sowie einer gesundheitlich bedenklichen AS-Exposition für den Imker bedeuten.
Langfristiges Ziel dieses Projekts ist es, ein mobiles, einfach handhabbares Gerät zur Detektion der AS-Konzentration in der Bienenstock-Luft während einer AS-Behandlung zu entwickeln.
Grundlage hierfür bietet ein kommerziell verfügbares Multigassensorsystem (PEN3, AIRSENSE Analytics GmbH, Schwerin).
Ziel der beschriebenen Vorversuche ist die generelle Eignungsprüfung des Multigassensorsystems PEN3 zur Detektion der hohen AS-Konzentration in Gasgemischen unter Bedingungen wie sie im Bienenstock während einer AS-Behandlung herrschen.
Als Messplatz zur Detektion von AS in Luft wurden zwei Systeme vorbereitet:
A) Eine Plexiglasbox mit einem Volumen von ca.1,9 l diente als Prüfkammer, wurde von einem Gasstrom befeuchteter synthetischer Luft durchströmt (50 mL min-1, 100 mL min-1 oder 300 mL min-1) und zur Temperierung auf 25 °C auf einer Heizmatte bzw. auf 35 °C in einem Ofen platziert. AS-Wasser-Gemische verschiedener Volumenverhältnisse (0-100%) wurden in einer Glasschale (Oberfläche Flüssigphase 9,6 cm2) in der Prüfkammer vorgelegt.
B) In einer durch eine Heizmatte auf 25 °C temperierten, zwei-zargigen Segeberger Beute wurden vier Messpunkte angebracht (davon drei in der oberen und einer in der unteren Etage) und 60%ige AS über einen Nassenheider-Verdampfer vertikal vorgelegt.
Zur Detektion des AS-Luft-Gemischs wurde das PEN3 Multigassensorsystem genutzt. Das zu untersuchende Gasgemisch wurde über die internen zehn Metalloxid-Halbleiterdetektoren (1-10) der PEN3 geleitet. Das so generierte Messsignal beschreibt ein Widerstandsverhältnis zwischen dem Widerstandwert zum Zeitpunkt der Messung (R) und dem elektrischen Widerstand bei der Nullluft-Messung (R0), wobei hier befeuchtete synthetische Luft mit einer reltativen Feuchte von 49 % ± 4 % oder Raumluft genutzt wurde. Gase unterschiedlicher Zusammensetzung können anhand der dargestellten Signalmuster verschiedener Sensoren voneinander unterschieden werden.
In beiden Messsystemen wiesen die Sensorelemente 1, 6, 7, 8 und 9 gesteigerte Sensitivitäten beim Vorliegen von Ameisensäure im Gasgemisch auf. Die größten Widerstandsverhältnisse zeigten dabei die Sensorelemente 6, 8 und 9, sodass hier von der höchsten Empfindlichkeit für AS auszugehen ist.
Basierend auf den erhobenen Messdatensätzen wurden Hauptkomponenten- (PCA) und lineare Diskriminanzanalysen (LDA) zur Dimensionsreduktion durchgeführt, um charakteristische Muster aus den Messsignalen zu extrahieren. Die PCA- und LDA-Plots für die jeweils bedeutsamsten Komponenten PC 1 und PC 2 bzw. LD 1 und LD 2 eines Versuchslaufs in der Plexiglasbox (A) bei einer Temperatur von 35°C, einem Volumenstrom von 300 mL min-1 und variablen Ameisensäure-Wasser-Volumenverhältnissen von 0 % bis 100 %. Deutlich erkennbar sind die Abhängigkeiten der Komponenten PC 1 und LD 1 (Abszissen) vom vorgelegten AS-Wasser-Volumenverhältnis. Unsere Ergebnisse zeigen, dass das Multigassensorsystem zur Bestimmung von AS in Luft unter ähnlichen Bedingungen wie bei einer AS-Behandlung im Bienenstock angewandt werden kann.
Die Versuche zeigen, dass die im PEN3 eingesetzten Metalloxid-Sensoren bzw. Metalloxidsensor-Arrays zur Detektion von AS in Luft auch bei höheren Konzentrationen als beispielsweise der MAK-Wert von 5 µmol/mol zur Überwachung des AS-Gehaltes in Bienenstöcken angewandt werden können. Aufgrund der Möglichkeit der quasi Echtzeit-Messdatengenerierung, der geringen Kosten kommerziell verfügbarer Sensorelemente, der Portabilität und der Möglichkeit zur Miniaturisierung zeichnen sich solche Messsysteme zukünftig durch eine besondere Praxisnähe aus. Diese Erkenntnisse sind Grundlage für eine Verbesserung des Detektionsverfahrens und zur Vorhersage über die Effizienz und Effektivität der Varroha-Milbenbehandlung.
In this paper, we introduce a nano aerial robot swarm for Indoor Air Quality (IAQ) monitoring applications such as occupational health and safety of (industrial) workplaces. The robotic swarm is composed of nano Unmanned Aerial Vehicles (UAVs), based on the Crazyflie 2.0 quadrocopter, and small lightweight Metal Oxide (MOX) gas sensors for measuring the Total Volatile Organic Compound (TVOC), which is a measure for IAQ. An indoor localization and positioning system is used to estimate the absolute 3D position of the swarm similar to GPS. A test scenario was built up to validate and optimize the swarm for the intended applications. Besides calibration of the IAQ sensors, we performed experiments to investigate the influence of the rotor downwash on the gas measurements at different altitudes and compared them with stationary measurements. Moreover, we did a first evaluation of the gas distribution mapping performance. Based on this novel IAQ monitoring concept, new algorithms in the field of Mobile Robot Olfaction (MRO) are planned to be developed exploiting the abilities of an aerial robotic swarm.
The presence of wastewater and air pollution has become an important risk factor for citizens, not only in terms of problems related to health risks, but also because of its negative impact on the country's image. For this reason, malodorous emission monitoring and control techniques are in high demand in urban areas and industries. The aim of this work is first to build an electronic nose (e-nose) and a Voltammetric Electronic tongue (VE-tongue) in order to study their ability to discriminate between polluted and clean environmental samples. Secondly, Thermal Desorption-Gas Chromatography-Mass Spectrometry (TD-GC-MS), and Solid Phase Micro Extraction-Gas Chromatography–Mass Spectrometry (SPME-GC-MS) are utilized to explain this discrimination by identifying specific compounds from these samples. Indeed, the e-nose, consisted of metal oxide semiconductor gas sensors, is used for the assessment of the studied odorous air and headspace samples from water and wastewater sites. Moreover, the VE-tongue, based on metal electrodes, is utilized to determine the patterns of the sensor array responses, which serve as fingerprints profiles of the analyzed liquid samples. Chemometric tools, such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), and Support Vector Machines (SVMs) are operated for the processing of data from the e-nose and the VE-tongue. By using the both systems, the analyses of headspace and liquid samples from the seven sites allow better discrimination. To explain the cause of the obtained discrimination, TD-GC-MS and SPME-GC-MS analyses are well performed to identify compounds related sites. According to these outcomes, the proposed e-nose and VE-tongue are proved to be rapid and valuable tools for analysis of environmental polluted matrices.
IMS trägt zur Luftfrachtsicherheit bei
Geltende Luftsicherheitsgesetze verpflichten Luftsicherheitsbehörden, Flughafenbetreiber und Fluggesellschaften umfassende Sicherheitsmaßnahmen auf den Flughäfen zu ergreifen, um die Gefahr möglicher terroristischer Bedrohungen zu erkennen und zu verhindern. Wenn ein verdächtiges Objekt durch Röntgenstrahlen identifiziert wurde, kann die IMS als schnelles Analyseverfahren vor Ort orthogonal zur Radiologie eingesetzt werden, um chemische Informationen über Gefahrstoffe wie Sprengstoffe oder Drogen vor dem Abflug zu erhalten.
Vor der Detektion von Sprengstoffen beginnt die Untersuchung eines verdächtigen Objekts mit der Probenahme mittels Wischprobensammlern. Eine Luftsicherheitskontrollkraft wischt dabei Oberflächen des Objekts mit einem Probensammler ab, um Partikel von Gefahrstoffen zu sammeln. Der beladene Probensammler wird anschließend in einen Probeneinlass eingeführt. Nach thermischer Desorption der gesammelten Stoffe erhält der Bediener (z. B. Luftsicherheitskontrollkraft) ein boolesches Ergebnis - "Alarm" oder "Kein Alarm".
Verfahren und Ergebnisse
In dieser Studie wurden drei Verfahren mit vier ECAC-zertifizierten ETD-Geräten zur Entwicklung eines Unsicherheitskonzeptes bezüglich der Probenahme (PN) angewandt:
I) direkte Probenaufnahme durch lösemittelbasierten Auftrag einer bekannten Sprengstoffmenge auf einem Probensammler,
II) Auftragung einer bekannten Menge eines gelösten Sprengstoffs auf einem 10 cm × 10 cm Substrat (Aluminium, Papier, Eisen und Polyvinylchlorid) und manuelle PN nach Lösemittelverdampfung,
III) lösemittelbasierter Sprengstoffauftrag auf eine PTFE- oder PTFE-beschichtete Glasfaseroberfläche, nach Lösemittelverdunstung trockene Übertragung auf das zu beprobende Substrat zur PN.
Nach dem binären Regressionsverfahren wurde die funktionale Abhängigkeit der Detektionswahrscheinlichkeit von einer bekannten Sprengstoffmasse mit einer Logit-Funktion beschrieben:
POD=1/(1+e^(-A·(m-B))).
Dabei ist POD die Wahrscheinlichkeit der Detektion für eine bekannte Sprengstoff-Masse, die Parameter A (logistische Wachstumsrate der Kurve) und B (m-Wert des Mittelpunktes des Sigmoids) sind geschätzte Parameter nach der Methode der kleinsten Quadrate, und m ist die Sprengstoffmasse.
Das entwickelte Messunsicherheitsmodell kombiniert quantitative Ergebnisse aus Wägen, Lösen und Pipettieren sowie qualitative Ergebnisse - "Alarm" oder "Kein Alarm" und die Unsicherheit der PN. Identifizierte Unsicherheitsursachen sind die Durchführung der Wischprobenahme, Staub, Lösemitteleffekte und die Unsicherheit bei der Herstellung von Testlösungen.
The present paper describes the development of a sensor material that changes its fluorescence in the presence of gaseous ammonia in a relevant concentration range. The implementation into a semi-automatic gas measurement device enables low-cost, precise, simple and fast monitoring of low con-centrations of harmful gases, like ammonia, and hence can help to improve the climate monitoring in livestock housing, barns or stables.
Design and Implementation of Smart Multisensor Monitoring System for Safe Workplaces with LoRaWAN
(2020)
This project addresses the application of safe workplaces in offices and chemical laboratories where indoor air quality plays an important role. The LoRaWAN (Long Range Wide Area Network) is used as a communication interface to make important sensor data globally accessible. The goal of the development is to create a sensor node and an online and offline solution that collects the data from the sensor nodes and stores it on a local server or in a cloud. In cooperation with the companies WISTA GmbH and IONOS, a test sensor network is going to be established in the Berlin-Adlershof area.
The chapter describes the application of electronic noses (multigas sensors) for the quality control of spices and spice mixtures. Electronic noses were successfully applied for headspace analysis of spices. It was demonstrated in many investigations that electronic noses can contribute to the characterization of spices and spice mixtures in order to distinguish spices and spice mixtures, differentiate by origin, growth seasons,and processing,indicate adulteration from original, detect mold infestation. Electronic noses can be used as a fast screening method to provide information about the product quality. However, it needs samples and methods for reference, careful training, and complex calibration to consider influencing and disturbing effects as well as the possible limitations of the instrumentation. The correlation to classical chemical analysis methods is always advisable. Machined olfaction methods are capable to support the sensory analysis; however, they cannot yet substitute them.
Ammonia and its conversion product ammonium have a strong negative impact on human health and ecosystems. Most ammonia measurements in ambient air are performed in the molar fraction range (0.5 to 500) nmol/mol. There is a need for reliable traceable ammonia gas standards as well as in situ analytical procedures for the monitoring of ammonia in ambient air.
The permeation method is an effective tool for dynamically generating precise gas standards with a low uncertainty in the concentration range of a few nmol/mol to several µmol/mol in an inert carrier gas, e. g. pure nitrogen or purified ambient air. Here, we present our ammonia gas standard generator as well as results of the characterisation of its individual components supporting the uncertainty assessment according to GUM for stable gas concentrations in this range.
In order to detect ammonia in the nmol/mol-range, a suitable sensor has to be developed. In this contribution, we therefore additionally present first approaches on the development of such a sensor using optical fluorescence as transduction mechanism due to its intrinsically high sensitivity and high spatial resolution. Incorporation of a fluorescent dye, which shows fluorescence enhancement in the presence of ammonia, into a polymer matrix allows to reversibly recognize low amounts of ammonia. It can be concluded that fluorescence sensor is a robust tool for measurements of ammonia; however it needs calibration for the planed use.
Different electronic sensor systems coupled with multivariate data analysis were applied to characterize and classify seven saffron samples and to verify their declared geographical origin. The proposed electronic sensing consists of a low-cost electronic nose (E-nose) based on metal oxide semiconductor sensors and a voltammetric electronic tongue (VE-tongue) based on voltammetric sensors. The ability of multivariable analysis methods such as Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA) and Support Vector Machines (SVMs) to classify the saffron samples according to their geographical origin have been investigated. Both PCA and HCA have shown an overlapping of E-nose responses. Moreover, the SVM analysis of the E-nose database reached a 66.07% success rate in the recognition of the saffron sample odour. On the other hand, good discrimination has been reached using PCA and HCA in the VE-tongue characterization case, besides a 100% accuracy in the saffron flavour recognition was attained. To validate the proposed electronic sensing systems, analytical chemical methods such as SPME-GC-MS and UV-Vis spectrophotometry were used. These analytical methods could be helpful tools to identify the composition of volatile compounds of the analysed saffron samples. Moreover, UV-Vis spectrophotometry was also used to determine the non-volatile profile of the samples from different geographic origins. It is demonstrated that the electronic sensing systems' findings are in a satisfactory correlation with the analytical methods. In the light of these results, we might say that the electronic systems offer a fast, simple and efficient tool to recognize the declared geographical origin of the saffron samples.
Die Varroose gilt weltweit als eine der bedeutendsten Erkrankungen der westlichen Honigbiene, Apis mellifera. Verursacht wird sie durch den Ektoparasiten Varroa destructor, der durch Saugen der Hämolymphe und Virenübertragung sowohl die Bienenbrut als auch die adulten Individuen schädigt.
Ohne imkerliche Unterstützung gehen betroffene Bienenvölker in der Regel innerhalb von drei Jahren ein. Als bewährte, häufige Behandlung wird flächendeckend 60%ige Ameisensäure (AS) - im Bienenstock appliziert über verschiedene Verdampfungssysteme - eingesetzt. Sie wirkt als einziger zugelassener Stoff gegen die Varroamilbe auch in die verdeckelte Brut hinein und birgt kein Risiko der Resistenzentwicklung.
Allerdings ist das therapeutische Fenster, der Bereich zwischen Milbenabtötung und Bienenschädigung, relativ schmal und die tatsächliche AS-Konzentration im Bienenstock stark abhängig von äußeren Einflussfaktoren, wie Temperatur, Luftfeuchte oder Applikationsart.
Eine Bestimmung der exakten AS-Konzentration im Bienenstock ist also notwendig, um einerseits das Wirkungsoptimum zu bestimmen und andererseits bei Übersteigen der Maximalkonzentrationen mit Folge-Schädigung der Bienen, ein rechtzeitiges Eingreifen der Imker zu ermöglichen.
In this paper, we introduce a nano aerial robot swarm for Indoor Air Quality (IAQ) monitoring applications such as occupational health and safety of (industrial) workplaces. The robotic swarm is composed of nano Unmanned Aerial Vehicles (UAVs), based on the Crazyflie 2.0 quadrocopter, and small lightweight Metal Oxide (MOX) gas sensors for measuring the Total Volatile Organic Compound (TVOC), which is a measure for IAQ. An indoor localization and positioning system is used to estimate the absolute 3D position of the swarm similar to GPS. A test scenario was built up to validate and optimize the swarm for the intended applications. Besides calibration of the IAQ sensors, we performed experiments to investigate the influence of the rotor downwash on the gas measurements at different altitudes and compared them with stationary measurements. Moreover, we did a first evaluation of the gas distribution mapping performance. Based on this novel IAQ monitoring concept, new algorithms in the field of Mobile Robot Olfaction (MRO) are planned to be developed exploiting the abilities of an aerial robotic swarm.
Immer mehr Multigassensoren
(2019)
Formic acid (FA) treatment as measure against the ectoparasitic mite, Varroa destructor, which infests the western honey bee, Apis mellifera, is usually performed twice a year. Although the therapeutic index is very narrow and the success of FA-treatment is highly dependent on various external factors, little is known about the local FA concentrations occuring in the hive. In this study we examined whether a commercially available odour measuring device (“electronic nose”) is suitable for measurements of high FA concentrations, as present during treatment. As measuring systems, two different setups were prepared for detection of FA concentrations in gas mixtures: A polymethyl methacrylate (PMMA) box was used to investigate whether the electronic nose is able to distinguish between different FA concentrations and a two-storied Segeberger hive to test under realistic conditions during bee-keeping.
In both experimental systems, the signals from the same sensor components (sensor type no. 1, 6, 7, 8 and 9) showed an increased sensitivity towards the presence of FA in the gas mixture. Principle component analysis (PCA) and linear discriminant analysis (LDA) allowed for identification of specific patterns in the measurement signals and showed clear correlations between the signals and the present FA concentration. These results indicate that the introduced commercial multi gas sensor system is suitable for detection of high FA concentrations, and therefore could be a starting point developing a detection method of FA. The future aim is to successfully monitor the efficiency and effectiveness of this anti-varroa-treatment.
Formic acid (FA) treatment as measure against the ectoparasitic mite, Varroa destructor, which infests the western honey bee, Apis mellifera, is usually performed twice a year. Although the therapeutic index is very narrow and the success of FA-treatment is highly dependent on various external factors, little is known about the local FA concentrations occuring in the hive. In this study we examined whether a commercially available odour measuring device (“electronic nose”) is suitable for measurements of high FA concentrations, as present during treatment. As measuring systems, two different setups were prepared for detection of FA concentrations in gas mixtures: A polymethyl methacrylate (PMMA) box was used to investigate whether the electronic nose is able to distinguish between different FA concentrations and a two-storied Segeberger hive to test under realistic conditions during bee-keeping.
In both experimental systems, the signals from the same sensor components (sensor type no. 1, 6, 7, 8 and 9) showed an increased sensitivity towards the presence of FA in the gas mixture. Principle component analysis (PCA) and linear discriminant analysis (LDA) allowed for identification of specific patterns in the measurement signals and showed clear correlations between the signals and the present FA concentration. These results indicate that the introduced commercial multi gas sensor system is suitable for detection of high FA concentrations, and therefore could be a starting point developing a detection method of FA. The future aim is to successfully monitor the efficiency and effectiveness of this anti-varroa-treatment.
Die Effizienz von Gassensoren zur sicheren Verwendung von Wasserstoff hängt wesentlich von der Reaktion des Sensors auf eine Änderung der Wasserstoffkonzentration ab. Daher wurde die Ansprechzeit von fünf im Handel erhältlichen Wasserstoffsensoren unterschiedlichen Messprinzips bestimmt. Experimente haben gezeigt, dass alle Sensoren die Anforderungen der Norm ISO 26142 übertreffen; es wurden Ansprechzeiten im Bereich (t90-Zeiten) von 2 s bis 16 s ermittelt. Die Ergebnisse können mit Exponential- oder Sigmoidalfunktionen approximiert werden. Es kann gezeigt werden, dass die Ergebnisse zum transienten Verhalten sowohl von den Betriebsparametern der Sensoren und Prüfverfahren als auch von den experimentellen Bedingungen wie Gaswechselrate sowie Konzentrationssprung abhängen.
This paper describes the development of a semi-automatic gas measurement device presenting potentially a broad range of applications, noteworthy in the agricultural sector. Non-reversible fluorescent molecular sensors were designed and syn-thesized. Upon, integration into a hydrogel matrix with an optimal ratio of co-solvents, the sensors reacting selectively to ammonia were illuminated by excitation light to produce a concentration-correlated fluorescence emission. An automated mechanical-elec-trical device initiates a given gas mixture and thus simulates con-centrations similar to a threshold value. The aim of this project is to develop a sensor or a low-cost method which can monitor low concentrations of harmful gases and aid in their elimination or regulation in livestock housing, barns or stables.
Die Varroose gilt weltweit als eine der bedeutendsten Erkrankungen der westlichen Honigbiene, Apis mellifera. Verursacht wird sie durch den Ektoparasiten Varroa destructor, der durch Saugen der Hämolymphe und Virenübertragung sowohl die Bienenbrut als auch die adulten Individuen schädigt.
Ohne imkerliche Unterstützung gehen betroffene Bienenvölker in der Regel innerhalb von drei Jahren ein. Als bewährte, häufige Behandlung wird flächendeckend 60%ige Ameisensäure (AS) - im Bienenstock appliziert über verschiedene Verdampfungssysteme - eingesetzt. Sie wirkt als einziger zugelassener Stoff gegen die Varroamilbe auch in die verdeckelte Brut hinein und birgt kein Risiko der Resistenzentwicklung.
Allerdings ist das therapeutische Fenster, der Bereich zwischen Milbenabtötung und Bienenschädigung, relativ schmal und die tatsächliche AS-Konzentration im Bienenstock stark abhängig von äußeren Einflussfaktoren, wie Temperatur, Luftfeuchte oder Applikationsart.
Eine Bestimmung der exakten AS-Konzentration im Bienenstock ist also notwendig, um einerseits das Wirkungsoptimum zu bestimmen und andererseits bei Übersteigen der Maximalkonzentrationen mit Folge-Schädigung der Bienen, ein rechtzeitiges Eingreifen der Imker zu ermöglichen.
Viele Sensoren sind auf dem Markt, die flüchtige organische Substanzen im Innenraum nicht nur messen, sondern gleichzeitig auch die Luftgüte bewerten. Damit diese Sensoren gute und vergleichbare Daten liefern, erarbeitet ein Fachausschuss der VDI/VDE-Gesellschaft Mess- und Automatisierungstechnik (GMA) eine neue VDI-Richtlinie.
IMS trägt zur Luftfrachtsicherheit bei Luftsicherheitsgesetze verpflichten Luftsicherheitsbehörden, Flughafenbetreiber und Fluggesellschaften umfassende Sicherheitsmaßnahmen auf den Flughäfen zu ergreifen, um Gefahren z. B. durch potenziell gefährliche Frachtgüter zu erkennen. Von der Europäische Zivilluftfahrt-Konferenz (ECAC) zertifizierte IMS-Geräte werden vor Ort an den Kontrollpunkten orthogonal zur Radiologie eingesetzt, um chemische Informationen von verdächtiger Fracht über Gefahrstoffe wie Sprengstoffe oder Drogen vor dem Verladen zu erhalten.
Vor der Detektion von Sprengstoffen beginnt die Untersuchung eines verdächtigen Objekts mit der Probenahme mittels Wischprobensammlern. Eine Luftsicherheitskontrollkraft wischt dabei Oberflächen des Objekts mit einem Probensammler ab, um Partikel von Gefahrstoffen zu sammeln. Der beladene Probensammler wird anschließend in einen Probeneinlass eingeführt. Nach thermischer Desorption der gesammelten Stoffe erhält der Bediener (z. B. Luftsicherheitskontrollkraft) ein boolesches Ergebnis - "Alarm" oder "Kein Alarm".
Verfahren und Ergebnisse
In dieser Studie wurden drei Verfahren mit vier ECAC-zertifizierten ETD-Geräten zur Identifizierung und Beurteilung der Probenahme (PN) entwickelt:
I) direkte PN durch lösemittelbasierten Auftrag einer bekannten Sprengstoffmenge auf einem Probensammler,
II) Auftrag einer bekannten Menge eines gelösten Sprengstoffs auf einem 10 cm × 10 cm Substrat (Aluminium, Papier, Eisen und Polyvinylchlorid) und manuelle PN nach Lösemittelverdampfung,
III) lösemittelbasierter Sprengstoffauftrag auf eine PTFE- oder PTFE-beschichtete Glasfaseroberfläche, nach Lösemittelverdunstung trockene Übertragung auf das zu beprobende Substrat zur PN.
Der Zusammenhang zwischen vorgelegter Sprengstoffmenge und der Detektionswahrscheinlichkeit (POD) erfolgt durch Anwendung des binären Regressionsverfahrens mit einer Logit-Funktion:
POD=1/(1+exp(-A(m-B)) )·100%
Dabei entspricht m der vorgelegten Sprengstoffmasse bis 1000 ng, Parameter A / ng-1 der logistischen Wachstumsrate der Kurve und Parameter B / ng dem m-Wert des Mittelpunktes des Sigmoids. Die Bestimmung der Parameter wurde nach der Methode der kleinsten Quadrate berechnet.
Das entwickelte Messunsicherheitsmodell kombiniert quantitative Ergebnisse aus Stammlösung und deren Verdünnungen sowie Stoffauftrag und qualitative Ergebnisse nach Anzeige "Alarm" oder "Kein Alarm". Dieses Auswerteverfahren wurde auf die Probenahme angewandt. Identifizierte Unsicherheitsursachen sind die Durchführung der Wischprobenahme, Staub, Lösemitteleffekte und die Unsicherheit bei der Herstellung von Testlösungen.
Ein Durchlaufkühler ist im Betrieb explodiert. Die zerborstenen Gehäuseteile aus Kunststoff führten zu einem Austreten der Kühlflüssigkeit am Betriebsort sowie zu einem Personenschaden mit Knalltrauma. Bei Funktionsprüfungen am beschädigten Gerät traten unerwartet, aber reproduzierbar Knalleffekte auf der Kupfer-Kühlschlange auf. Ein möglicher Mechanismus konnte im Labor durch Synthese von Kupferazid auf Kupferproben und Auslösung vergleichbarer Knalleffekte nachgestellt werden. Damit ist die Plausibilität des beschriebenen Schadensereignisses mit diesem oder einem ähnlich reagierenden Stoff belegt. Ein eindeutiger Nachweis darüber, dass beim aufgetretenen Schadensfall dieselbe chemische Reaktion stattgefunden hat ist nicht möglich, da die Belag-Überreste aus dem explodierten Kühlgerät für eine Analyse nicht mehr in ausreichender Menge verfügbar waren.
Pollution through emission of toxic gases becomes an increasing problem for the environment in agricultural, industrial and urban areas. In future, environmental emissions as well as ambient air must be monitored at even lower concentrations as nowadays. Consequently, demands arouse for measuring concentrations as low as the lower ppm or even ppb range. Current state-of-the-art technologies, as for instance electrochemical sensors, have reached their limits in this regard.
The developed ammonia gas standard generator produces standard gas mixtures which comply with the metrological traceability for ammonia gas standards in the desired environmentally relevant measurement range of e. g. 0.5 to 500 nmol/mol. This gas standard preparation method is based on the permeation of ammonia through a membrane at a constant temperature as well as the mixing of this permeated gas with a carrier gas to adjust a gas standard of known concentration. The ammonia gas standard is suitable for the calibration of standard optical methods, e. g cavity ring-down spectroscopy (CRDS) and multi-gas sensors.
The detection of gaseous ammonia in the lower ppm or even ppb range is obtained by incorporation of a fluorescent dye, which shows fluorescence enhancement in the presence of the analyte, into a polymer support being responsible for the accumulation of the analyte. The use of optical fluorescence as transduction mechanism enables high sensitivity as well as high temporal resolution. Here, we present first results on such a sensor system including the use of the developed gas standard generator for calibration issues. Additional benefits, particularly of fluorescence-based sensors, are their capability for miniaturization and potential multiplex mode. Beside the development of a highly sensitive and selective sensor, the integration of such systems into mobile sensor devices is addressed.
These sensors and sensor systems are developed and will be validated and operated in form of functional models for the application areas, structure-integrated sensors and mobile multi-gas sensors.
The fluorescence properties of three molecular rotors, related to 4-dimethylamino-4-nitrostilbene (4-DNS), are studied versus different diesel/kerosene blends. In nonviscous solvents, these compounds can populate a twisted intramolecular charge transfer state which deactivates nonradiatively, successfully suppressing fluorescence emission. Solution experiments with diesel/kerosene blends showed a good linear correlation between the fluorescence intensity of the probe molecules and the diesel fraction of the blend. The dyes have been immobilized on paper, retaining their fluorescence behavior, i.e., negligible emission in the presence of nonviscous organic solvents and increasing fluorescence when the environment is increasingly viscous. When the impregnated paper is devised as a test strip, the latter is compatible with a newly designed smartphone reader system, which allows in-the-field measurements. The method can safely detect the presence of kerosene in diesel at ≥7%, which competes favorably with current standard methods for the detection of diesel adulteration.
Ammonia and its reaction products can cause considerable damage of human health and ecosystems, increasing the necessity for reliable and reversible sensors to monitor traces of gaseous ammonia in ambient air directly on-site or in the field. Although various types of gas sensors are available, fluorescence sensors have gained importance due to advantages such as high sensitivity and facile miniaturization.
Here, we present the development of a sensor material for the detection of gaseous ammonia in the lower ppm to ppb range by incorporation of a fluorescent dye, which shows reversible fluorescence modulations as a function of analyte concentration, into a polymer matrix to ensure the accumulation of ammonia. A gas standard generator producing standard gas mixtures, which comply with the metrological traceability in the desired environmentally relevant measurement range, was used to calibrate the optical sensor system. To integrate the sensor material into a mobile device, a prototype of a hand-held instrument was developed, enabling straightforward data acquisition over a long period.
Because ammonia and its reaction products can cause considerable damage to human health and ecosystems, there is a need for reliably operating and reversibly interacting sensor materials to monitor traces of gaseous ammonia in ambient air, which at best can be used on-site for in-the-field measurements. Herein, the development of a sensor material for gaseous ammonia in the lower ppm to ppb range using optical fluorescence as transduction mechanism is presented. A fluorescent dye, which shows reversible fluorescence enhancement in the presence of ammonia is incorporated into a polymer matrix, the latter to ensure the accumulation of ammonia. The sensor material is integrated into a prototype of a miniaturized sensor device, facilitating long-term operation. To calibrate the optical sensor system a gas standard generator, producing standard gas mixtures, is used, leading to a sensitivity down to lower ppm concentrations of ammonia.
Pollution through emission of toxic gases is an increasing problem for the environment. It affects similarly agricultural, industrial and urban areas. In future, environmental emissions in ambient air must be monitored at even lower concentrations as nowadays. One environmental relevant compound is ammonia and its conversion product ammonium that have strong negative impact on human health and ecosystems. Most ammonia measurements in ambient air are performed in the range below 1000 nmol·mol-1 and thus there is a need for reliable traceable ammonia gas standards and in addition in situ analytical procedures for monitoring (in ambient air to avoid that thresholds are exceeded). Therefore, the use of reference materials is necessary for development accompanying test or for calibration, e. g. of structure-integrated sensors and mobile multi-gas sensors.
The developed gas standard generator produces gas mixtures that comply with the metrological traceability for ammonia gas standards in the desired environmentally relevant measurement range. The method is based on the permeation of ammonia through a membrane at constant temperature and pressure. The resulting ammonia penetrant gas flow is then mixed with a carrier gas flow to generate a gas standard flow of known concentration. The dynamic rage is enlarged by using a two dilution steps. Depending on the permeation rate, generable molar fractions are possible in the range nmol·mol-1 to a few µmol·mol-1. We present the design of an ammonia gas standard generator and first results of the characterisation of its individual components supporting the uncertainty assessment according to GUM for stable gas concentrations in this range. The relative uncertainty of the generated ammonia gas standard is smaller than 4 % (k = 2).
Die Spurenfeuchte von technischen Gasen kann zuverlässig mit coulometrischen Feuchtesensoren bestimmt werden. Das Prinzip dieser Sensoren basiert auf der Absorption von Wasser in einer hygroskopischen Schicht und anschließenderelektrolytischer Zersetzung. Die Kalibrierung der Sensoren erfolgte mit einem Spurenfeuchtegenerator bei Frostpunkttemperaturen kleiner als -30 °C bzw. einem Volumenanteil kleiner als 376 µL·L-1. Die generierte Feuchte wurde zusätzlich zu den coulometrischen Sensoren mit einem Taupunktspiegelhygrometer, welches als Referenz diente, gemessen. Zwischen dem coulometrischen Sensorsignal und der gemessenen Referenzfeuchte wurde eine empirische nichtlinare Funktion gefunden. Die resultierende Kalibrierungsfunktion, die aus zwei Parametern besteht, wurde hinsichtlich ihrer Messunsicherheit bewertet.
Zusätzlich erfolgt die Überprüfung der Kalibrierparameter mittels einfaktorieller Varianzanalyse (ANOVA). Die ANOVA zeigte, dass eine gemittelte Funktion für die Feuchtigkeitbestimmung in Stickstoff, Helium und synthetischer Luft für mehrere Sensoren angewendet werden kann.
Mit coulmetrischen Sensoren ist es möglich, die Spurenfeuchte in technischen Gasen mit einer erweitereten Unsicherheit hinsichtlich der Frostpunkttemperatur kleiner als 2,1 K zu ermitteln.
Planar coulometric sensors were tested in humidified synthetic air at various gas temperatures. Generated frost point temperature in the gas ranged from -30 °C to -60 °C and were measured by coulometric sensors and in addition by a calibrated dew point hygrometer. The gas temperatures, which were measured by a calibrated Pt100 sensor, were set to -20 °C, 0 °C, 23 °C, 40 °C, 50 °C, and 60 °C during the experiments. Empiric nonlinear functions were calculated between the generated humidity and the sensor signals. In comparison to the measured signals at 23 °C, the sensor signals were lower at the other gas temperatures. The measurements at 60 °C showed indistinct results due to a great signal noise. The response behavior of the sensors was similar at 23 °C, 40 °C and 50 °C. In contrast to that, the sensors reacted slowly at a gas temperature of -20 °C and 0 °C. In summary, with coulometric sensors it was possible to measure continuously trace humidity with an expanded uncertainty below 2 K.
Innovation is the catalyst for the technology of the future. It is important to develop new and better technologies that can continuously monitor the environmental impact, e.g., for air quality control or emission detection. In the recently at BAM developed Universal Pump Sensor Control (UPSC3) module, different components and sensors are fused. The combination of the individual components makes the UPSC3 module an excellent monitoring and reference system for the development and characterization of gas specific sensors. Measurements over long periods are possible, for mixed gas loads or for certain gas measurements. The system is part of a mobile sensor network of several sensor units, which can also be used as standalone systems.
The motivation and objective of this research is to develop gas sensors based on fluorescence detection with range of ppm / ppb. For this task a reference system is required, which contains volatile organic compound (VOC) sensors for reference data from different scenarios. The integrated multi-sensor unit can measure different gases through the integrated 3-fold VOC sensor, which can be adapted to the addressed scenario. . The system-integrated flow control, with pump and flow sensor, allows the gas molecules to be transported directly to the VOC sensor. The entire measurement is permanently stored on an integrated memory card. If the previously determined limit range is exceeded, an alarm is generated. The system is an important tool towards further developments in the field of gas sensors and is primarily used for the validation of chemically based gas sensors.
Leaking methane (CH4) from infrastructures, such as pipelines and landfills, is critical for the environment but can also pose a safety risk. To enable a fast detection and localization of these kind of leaks, we developed a novel robotic platform for aerial remote gas sensing. Spectroscopic measurement methods for remote sensing of selected gases lend themselves for use on mini-copters, which offer a number of advantages for inspection and surveillance over traditional methods. No direct contact with the target gas is needed and thus the influence of the aerial platform on the measured gas plume can be kept to a minimum. This allows to overcome one of the major issues with gas-sensitive mini-copters. On the other hand, remote gas sensors, most prominently Tunable Diode Laser Absorption Spectroscopy (TDLAS) sensors have been too bulky given the payload and energy restrictions of mini-copters. Here, we present the Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS), which combines a novel lightweight TDLAS sensor with a 3-axis aerial stabilization gimbal for aiming on a versatile hexacopter. The proposed system can be deployed in scenarios that cannot be addressed by currently available robots and thus constitutes a significant step forward for the field of Mobile Robot Olfaction (MRO). It enables tomographic reconstruction of gas plumes and a localization of gas sources. We also present first results showing its performance under realistic conditions.
In the KonSens Project, sensor systems are developed, validated, and operated in form of functional models for the application areas Structure Integrated Sensors and Mobile Multi-gas Sensors. Key aspects are the detection and evaluation of corrosion processes in reinforced concrete structures as well as the detection and quantification of very low concentrations of toxic gases in air. The adaption of sensor principles from the lab into real-life application including appropriate communication techniques is a major task.
In recent years, Structural Health Monitoring have gained in importance, since growing age of buildings and infrastructure as well as increasing load requirements demand for reliable surveillance methods. In this regard, the project follows two strategies: First, the development and implementation of completely embedded sensor systems consisting of RFID-tag and in situ sensors, and their further application potential (e.g. for precast concrete elements, roadways, wind power plants, and maritime structures). Secondly, the development of a long-term stable, miniaturized, fiber optic sensor for a ratiometric and referenced measurement of the pH-value in concrete based on fluorescence detection as an indicator for carbonation and corrosion.
Environmental pollution through emission of toxic gases becomes an increasing problem not only in agriculture (e.g. biogas plants) and industry but also in urban areas. This leads to increasing demand to monitor environmental emissions as well as ambient air and industrial air components in many scenarios and in even lower concentrations than nowadays. The selectivity of luminescence-based sensors is enabled by the combination of the sensing dye and the material, which is used as accumulation medium for concentration of the analyte. This principle allows for developing gas sensors with high selectivity and sensitivity of defined substances. Additional benefits, particularly of fluorescence-based sensors, are their capability for miniaturization and potential multiplex mode. Objective is the development and implementation of sensors based on fluorescence detection for defined toxic gases (ammonia, hydrogen sulfide, ozone, and benzene) with sensitivity in the low ppm or even ppb range. Additionally, the integration of such sensors in mobile sensor devices is addressed.
Trace humidity was measured by using miniaturized planar coulometric sensors in technical gases such as hydrogen, nitrogen, helium, nitrous oxide, and synthetic air. Frost point temperatures tf in the gases ranged from −60 °C to −30 °C, which is equivalent to a vapour mole fraction xv from 10 μmol mol−1 to 376 μmol mol−1. In addition, the generated humidity was determined by using a precision dew point hygrometer as reference. Nonlinear calibration functions were calculated that correlated electric current (sensor signal) and reference humidity. Parameters of functions were tested with one-way analysis of variances (ANOVA) to prove if all used sensors had a similar behavior in the same gas during experiments. Results of ANOVA confirmed that averaged functions can be applied for trace humidity measurement in nitrogen, helium, nitrous oxide, and synthetic air. The calculated functions were negligibly different for nitrogen, helium, and synthetic air. In humidified nitrous oxide, a minor change of parameters was observed due to lower electrical currents. In total contrast to that, the measured sensor signals were significantly higher in humidified hydrogen and each sensor required its own calibration function. The reason was a recombination effect that favoured multiple measurements of water molecules. Nevertheless, it was possible to measure continuously trace humidity in all tested gases by using coulometric sensors with an expanded uncertainty below 2 K (k = 2).
Especially trace amounts of water vapour in gases can be reliably determined by coulometric trace humidity sensors. The principle of these sensors is based on water vapour absorption in a hygroscopic layer and its subsequent electrolytic decomposition. The calibration of sensors was performed in the humidity range, expressed as frost point temperature, from −30°C to −80°C . This range is equivalent to volume fractions smaller than 376 µL·L−1. Generated humidity was measured with coulometric sensors and a chilled dew point hygrometer that was used as reference. An empirical non-linear function was found between sensor signal and measured reference humidity. This function consists of two parameters with a measurement uncertainty. Both calibration parameters were checked by means of one-way analysis of variance. It showed that gas specific function can be used for humidity measurement in nitrogen, hydrogen, dinitrogen monoxide, compressed and synthetic air. It is possible to determine trace humidity in all tested gases with an expanded uncertainty less than 2.1 K (coverage factor k=2 ) regarding frost point temperature.
Moisture content and water activity are important parameters of product characterization; thus, an exact determination is necessarily required in a wide range of industrial applications. Moisture content of materials is the content of non-chemically bound water in a solid or liquid. Water activity (aW) is a characteristic/parameter of the non-chemically bound ("free") water in materials and is measured as humidity over a solid/liquid surface at constant temperature (equilibrium moisture content). It is an important parameter to characterize the quality of pharmaceutical and food products. In our contribution, we present a developed device for staged determination of water activity and moisture content of liquid and solid materials.
Leaking methane from infrastructures, such as pipelines and landfills, is critical for the environment but can also pose a safety risk. To enable a fast detection and localization of these kind of leaks, BAM developed a novel robotic platform for aerial remote gas sensing. Spectroscopic measurement methods for remote sensing of selected gases lend themselves for use on mini-copters, which offer a number of advantages for inspection and surveillance over traditional methods. No direct contact with the target gas is needed and thus the influence of the copter downwash on the measured gas plume can be kept to a minimum. This allows to overcome one of the major issues with gas-sensitive mini-copters. On the other hand, remote gas sensors, most prominently Tunable Diode Laser Absorption Spectroscopy (TDLAS) sensors have been too bulky given the payload and energy restrictions of mini-copters. Here, we present the Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS), which combines a novel lightweight TDLAS sensor with a 3-axis aerial stabilization gimbal for aiming on a versatile multicopter. The proposed system can be deployed in scenarios that cannot be addressed by currently available systems and thus constitutes a significant step forward for the field of Mobile Robot Olfaction (MRO). It enables tomographic reconstruction of gas plumes and a localization of gas sources. We also present first results showing its performance under realistic conditions.
Emissions of ammonia into the environment are mainly caused by agriculture, but also by combustion processes in waste and by road traffic. Even at low concentrations, this substance is not only an odour nuisance, but also a substance with ecological and climatic relevance. Therefore, BAM tested commercial electrochemical, and metal oxide based sensors, which have limited suitability for measuring in the environmental molar fraction range. Alternatively, own developments for the detection of ammonia in the trace range were implemented, wherein the analyte is measured by changing the fluorescence of a BODIPY dye at 550 nm by means of a portable fluorescence sensor directly from the gas phase. For the calibration of ammonia sensors and measuring instruments, a stationary system based on the mixture of certified test gases from pressure cylinders with calibrated mass flow controllers is available. A test gas generator was developed for on-site calibration and testing of sensors and measuring devices. The generation of ammonia-containing gases in the environmental relevant range of levels below 1000 nmol/mol is carried out by the permeation method according to ISO 6145-10. For the traceability of ammonia, standards are provided and further developed by the National Metrological Institutes and designated institutes. Metrological standards are based on SI units and are a basis for traceability of sensors or gas analysers.
Der Beitrag präsentiert die erarbeiteten technischen Richtlinien zur Anwendung und Prüfung von Multigassensoren innerhalb der Richtlinienreihe VDI/VDE 3518 sowie in diesem Zusammenhang die Möglichkeiten der Sensorprüfung im akkreditierten Prüflabor des Fachbereichs 8.1 der BAM. Im Speziellen wird das in Kürze veröffentlichte Blatt 3 der Richtlinienreihe vorgestellt, das Bezug auf Multigassensoren für geruchsbezogene Messungen mit elektronischen Nasen nimmt.
Ammoniakemissionen in die Umwelt erfolgen insbesondere durch die Landwirtschaft (93,6 %), aber auch durch Verbrennungsprozesse in der die Abfallwirtschaft (2,3 %) und den Straßenverkehr (1,8 %). Dieser Stoff ist selbst in geringen Konzentrationen nicht nur eine Geruchsbelästigung, sondern auch eine Substanz mit ökologischer und klimatischer Relevanz.
Die Bestimmung von Ammoniak in relevanten Konzentrationen von kleiner 25 μg m-3 erfolgt im Allgemeinen über NH4+ als Analyten, spektralfotometrisch oder mit der Ionenchromatographie nach Überführung in die flüssige Phase. Wegen der niedrigen Konzentrationen an Ammoniak in der Außenluft wird meist eine gesammelte Probe verwendet oder die Bestimmung erfolgt nach einer aktiven, anreichernden Probenahme.
Die eigenen Arbeiten sollen dazu beitragen, die Ammoniak-Bestimmung in der Außenluft präziser, sowie schneller und kostengünstiger zu machen.
Die BAM prüfte daher kommerzielle elektrochemische und Metalloxid-basierte Sensoren, die für diesen Konzentrationsbereich aber nur bedingt geeignet sind. Deshalb wurden alternativ eigene Entwicklungen zum Nachweis von Ammoniak im Spurenbereich aufgenommen, wobei der Analyt über die Änderung der Fluoreszenz eines BODIPY-Farbstoffs bei 550 nm mittels eines portablen Fluoreszenz-Sensors direkt aus der Gasphase gemessen wird.
Zur Kalibrierung von Ammoniak-Sensoren und -Messgeräten steht ein stationäres System basierend auf der Mischung von zertifizierten Prüfgasen aus Druckflaschen mit kalibrierten Massendurchfluss-regler (MFC) zur Verfügung. Darüber hinaus erfolgt eine chemische Analyse der verwendeten Gasgemische mittels eines Massenspektrometers.
Für die Kalibrierung und Prüfung von Sensoren und Messgeräten vor Ort wurde ein mobiles Prüfsystem entwickelt. Die Generierung von Ammoniak-haltigen Gasen im Spurenbereich von 0,5 nmol/mol bis 500 nmol/mol erfolgt durch das Permeationsverfahren nach ISO 6145-10.
Für die Realisierung der Rückführbarkeit der Ammoniakbestimmung werden von den Nationalen Metrologischen Instituten sowie designierten Instituten Standards bereitgestellt und auch weiterentwickelt. Die primären metrologischen Standards beruhen auf SI-Einheiten und sind die Basis für eine Rückführbarkeit der Sensoren bzw. Analysengeräte.
This article describes the application of the ion mobility spectrometry (IMS) as a technical link in the screening within the airfreight transport chain. Air freight is of very important also for German foreign trade. Every year around 4.3 Mt of freight are loaded at German airports and transported by air planes. The average value of a transported metric ton freight was approximately 81,000 € in 2015. Nearly 50 percent of the total air freight is transported in passenger planes as belly freight. Measures are necessary to detect illegal, dangerous items such as weapons, ammunition or improvised explosive devices (IED) to protect against attacks on air traffic security. The aim is to increase security in air traffic and at the same time contemporary increasing or at least unchanged efficiency in the airfreight transport chain.
IMS is a suitable instrumental technology for the trace detection of explosives (ETD) and their precursors orthogonal to radiological x-ray measurements on suspicious freight within 30 seconds and per EU regulation 2015/1998, section 6.2. The ECAC* certified ETD system QS-B220 was used. The IMS performance is demonstrated on three target compounds, TNT, RDX and PETN. The results’ evaluation of this semi-quantitative screening is carried out by using statistical methods for reliability assessment, such as probability of detection (POD) and receiver operating characteristic (ROC). Their detection limits with a POD = 0.90 are determined after swab sampling on various surfaces. These screening results provide an objective decision-making aid to responsible control personnel in addition to x-ray measurements, whether there are or are no dangerous substances or objects in the cargo.
*) ECAC = European Civil Aviation Conference
The objective of this work is to report the improvement obtained in the discrimination of complex aroma and taste with subtle differences in odor and flavor, by the use of fast suitable procedures for the cases of measurements in the field demanding decision-making in real time. The proposed electronic sensing systems, formed by an E-nose and VE-tongue, were used to discriminate cumin cultivars from different geographical origins, as well as to quantify the cumin adulteration percentages by using unsupervised and supervised chemometric tools. Thus, the results obtained are sufficiently encouraging as a starting point for the development of new electronic sensing systems with more improvement such the reliability of the sensors’ performance as well as the chemometric tools in order to deal with a complex dataset.
Moisture content and water activity are important parameters for quality characterization of products like bulk materials, powders, granules. Thus, an exact determination is necessarily required in a wide range of industrial applications. Moisture of materials is the content of non-chemically bound water in a solid or liquid. Water activity (aW) is a characteristic/parameter of the non-chemically bound ("free") water in materials and is measured as humidity over a solid/liquid surface at constant temperature (equilibrium moisture content). It is an important parameter to characterize the quality of e. g. pharmaceutical and food products. In our contribution, we present the developed MOISHUM device for staged determination of water activity and moisture content of liquid and solid materials.
The efficiency of gas sensor application for facilitating the safe use of hydrogen depends considerably on the sensor response to a change in hydrogen concentration. Therefore, the response time has been measured for five different-type commercially available hydrogen sensors. Experiments showed that all these sensors surpass the ISO 26142 standard; for the response times t90 values of 2 s to 16 s were estimated. Results can be fitted with an exponential or sigmoidal function. It can be demonstrated that the results on transient behaviour depend on both the operating parameters of sensors and Investigation methods, as well as on the experimental conditions: gas change rate and concentration jump.
This work presents the testing of a developed elec¬tronic nose for outdoor odour nuisance monitoring. The sensor system consists of a sampling system, a measuring cell equipped with commercially available low-cost gas sensor elements and a data acquisition system. The sensor testing showed that the developed prototype is able to distinguish, identify and partially quantify individual odorous substances like ethanol, ammonia and hydrogen sulphide. Ethanol and ammonia could even be detected below or near their odour threshold.
In industrial environments, airborne by-products such as dust and (toxic) gases, constitute a major risk for the worker’s health. Major changes in automated processes in the industry lead to an increasing demand for solutions in air quality management. Thus, occupational health experts are highly interested in precise dust and gas distribution models for working environments. For practical and economic reasons, high-quality, costly measurements are often available for short time-intervals only. Therefore, current monitoring procedures are carried out sparsely, both in time and space, i.e., measurement data are collected in single day campaigns at selected locations only. Real-time knowledge of contaminant distributions inside the working environment would also provide means for better and more economic control of air impurities. For example, the possibility to regulate the workspace’s ventilation exhaust locations can reduce the concentration of airborne contaminants by 50%.
To improve the occupational health and safety of (industrial) workplaces, this work aims for developing a swarm of gas-sensitive aerial nano robots for monitoring indoor air quality and for localizing potential emission sources.
In this paper, we present an autonomous aerial robot to reconstruct tomographic 2D slices of gas plumes in outdoor environments. Our platform, the so-called Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS) combines a lightweight Tunable Diode Laser Absorption Spectroscopy (TDLAS) sensor with a 3-axis aerial stabilization gimbal for aiming on a versatile octocopter. The TDLAS sensor provides integral gas concentration measurements but no information regarding the distance traveled by the laser diode's beam or the distribution of the gas along the optical path. We complemented the set-up with a laser rangefinder and apply principles of Computed Tomography (CT) to create a model of the spatial gas distribution from these integral concentration measurements. To allow for a rudimentary ground truth evaluation of the applied gas tomography algorithm, we set up a unique outdoor test environment based on two 3D ultrasonic anemometers and a distributed array of 10 infrared gas transmitters. We present first results showing the 2D plume reconstruction capabilities of the system under realistic conditions.
KonSens (Kommunizierende Sensorsysteme für die Bauteil- und Umweltüberwachung) - Projektergebnisse
(2019)
Im Projekt KonSens werden für die Anwendungsbeispiele bauteilintegrierte Sensorik für Betonkomponenten und mobile Multigassensorik Sensorsysteme in Form von Funktionsmustern entwickelt, validiert und angewendet. Schwerpunkte liegen einerseits in der Detektion und Bewertung von Korrosionsprozessen in Beton und andererseits in der Detektion und Quantifizierung sehr geringer Konzentrationen toxischer Gase in der Luft. Dabei ist die Adaption der sensorischen Methoden aus dem Labor in reale Messumgebungen inklusive geeigneter Kommunikationstechnik ein wichtiger Aspekt.
An equation for wind vector estimation using a multirotor aircraft as a flying anemometer is shown. To compute the wind vector an estimate of the thrust of the aircraft is required, which is related to the rotational speed of the rotors. Hence, a sensing system for the rotational speed using phototransistors is presented.
Der Beitrag präsentiert die erarbeiteten technischen Richtlinien zur Anwendung und Prüfung von Multigassensoren innerhalb der Richtlinienreihe VDI/VDE 3518 sowie in diesem Zusammenhang die Möglichkeiten der Sensorprüfung im akkreditierten Prüflabor des Fachbereichs 8.1 der BAM. Im Speziellen wird das in Kürze veröffentlichte Blatt 3 der Richtlinienreihe vorgestellt, das Bezug auf Multigassensoren für geruchsbezogene Messungen mit elektronischen Nasen nimmt.
The lecture about gas sensor characterization and calibration contains the content of 3S: Sensitivity, selectivity and stability, sensor drift, aging and poisoning as well as gas mixing systems for laboratory and field calibration, measurement uncertainty for sensor calibration and traceable calibration of gas sensor systems.
QI-Digital is a joined project aiming at digitalising Quality Infrastructure (QI) processes involving standardization, conformity assessment, accreditation, metrology, and market surveillance [1]. Federal institute of material research and testing (BAM) is working on the creation of a digital calibration certifi-cate (DCC) to achieve digital metrological traceability and conformity assessment. The utilisation of machine readable and executable DCCs in the XML format is demonstrated on an example of a tem-perature measurement at a hydrogen refueling station. The certificates will be retrieved and analysed automatically at a Process Control System or at a Digital Twin.
Es handelt sich hierbei um die erste Veröffentlichung einer verifizierbaren eAttestation (DCC mit DAkkS-Siegel). Sie wurde vom akkreditierten Kalibrierlabor D-K-11075-08, im Rahmen des QI-Digital Vorhabens, für den Fachbereich 8.1 erstellt und dient im Zusammenhang mit dem Vortrag "Digitale Kalibrierzertifikate – die Umsetzung in akkreditierten Laboratorien" auf dem 324. PTB-Seminar "Berechnung der Messunsicherheit – Empfehlungen für die Praxis" als Anschauungsmaterial für die Digitalisierung in der Metrologie.
The project "SealWasteSafe" of the Bundesanstalt für Materialforschung und -prüfung (BAM, Berlin) deals with sealing structures applied for underground disposal of nuclear waste from two perspectives: (1) material improvement for application in sealing constructions and (2) feasibility study regarding multi-sensor approaches to ensure quality assurance and long-term monitoring.
One specimen of 150 l made of alkali-activated material, which was found innovative and suitable for sealing constructions based on preliminary laboratory studies, and, for comparison purpose, another one made of salt concrete, are manufactured with an integrated multi-sensory setup for quality assurance and long-term-monitoring. The specimens were left in their cast form and additionally thermally insulated to simulate the situation in the repository. The multi-sensory concept comprises RFID technology embedded in the specimens suppling material temperature and moisture measurements, integrated fibre optic sensing allowing strain measurement and acoustic emission testing for monitoring possible crack formation. Overall, the suitability and the functionality of the sensors embedded into and attached to strongly alkaline (pH > 13 for the AAM) and salt corrosive (NaCl) environment was proven for the first 672 h.
First temperature measurement based on RFID succeeded after 626 h for the alkali-activated material and after 192 h for the conventional salt concrete. Strain measurement based on distributed fibre optic sensing turned out the alkali-activated material with > 1 mm m-1 undergoing approximately twice the compression strain as the salt concrete with strains < 0.5 mm m-1. In contrast, the acoustic emission first and single hits representing crack formation in numbers, was found for alkali-activated material half of that detected at the salt concrete.
Der Vortrag zum Mess- und Prüfverfahren mit verschiedenen Sensortechnologien und Ultraschallwellen beinhaltet die Themen:
Metrologie zur Wasserstoffspeicherung - Euramet-Vorhaben "MefHySto",
Erkennung von freigesetztem Wasserstoff sowie die Bestimmung des Wasserstoff-Luftverhälntisses mit Gassensoren, zerstörungsfreie Fehlstellenerkennung mit integriertem Zustandsüberwachungssystem basierend auf geführten Ultraschallwellen zur Lebensdauerüberwachung von Composite-Behältern (Wasserstoffspeicher) sowie faseroptische Sensorik zur Schadenfrüherkennung von Wasserstoffspeichern aufgrund erkennbarer Dehnungsänderungen an Druckbehältern.