@inproceedings{Maiwald, author = {Maiwald, Frederik}, title = {Simulation of Pyrometer Based Temperature Measurement Systems using Non-Sequential Raytracing}, series = {Applied Research Conference 2018, ARC 2018, 10 July 2018, Deggendorf}, booktitle = {Applied Research Conference 2018, ARC 2018, 10 July 2018, Deggendorf}, editor = {Mottok, J{\"u}rgen and Reichenberger, Marcus and Bogner, Werner}, publisher = {pro Business GmbH}, address = {Berlin}, pages = {168 -- 171}, language = {en} } @inproceedings{Quandt, author = {Quandt, Benjamin}, title = {Effect of the Detection Spot Size on pyrometric Temperature Signal at quasi-simultaneous Laser Transmission Welding}, series = {Applied Research Conference 2018, ARC 2018, 10 July 2018, Deggendorf}, booktitle = {Applied Research Conference 2018, ARC 2018, 10 July 2018, Deggendorf}, editor = {Mottok, J{\"u}rgen and Reichenberger, Marcus and Bogner, Werner}, publisher = {pro Business GmbH}, address = {Berlin}, pages = {261 -- 264}, language = {en} } @article{vanderWeerdBierlMatysik, author = {van der Weerd, Bastiaan and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Trends in Electrochemical Sensing of Blood Gases}, series = {Bioanalytical Reviews}, volume = {6}, journal = {Bioanalytical Reviews}, publisher = {Springer}, address = {Berlin}, doi = {10.1007/11663_2016_1}, pages = {263 -- 280}, abstract = {The monitoring of partial pressures of the blood gases carbon dioxide (pCO2) and oxygen (pO2) is of great importance in clinical diagnostics. The measure of pCO2 and pO2 provides essential information about the patient's metabolism, gas exchange, ventilation, and acid-base homeostasis. The conventional electrochemical methods for clinical blood gas analysis are based on the potentiometric Severinghaus sensor for carbon dioxide and the amperometric Clark sensor for oxygen. These techniques are well established and are only shortly discussed in this overview. However, in recent years a variety of modifications of these classical sensor concepts and new approaches of electrochemical sensing of pCO2 and pO2 have been introduced. This review summarizes recent developments in this field and discusses the potential for future applications in clinical blood gas analysis.}, language = {en} } @inproceedings{RaabRacekKraemeretal., author = {Raab, Peter and Racek, Stanislav and Kr{\"a}mer, Stefan and Mottok, J{\"u}rgen}, title = {Reliability of Task Execution during Safe Software Processing}, series = {15th Euromicro Conference on Digital System Design, Cesme, Turkey}, booktitle = {15th Euromicro Conference on Digital System Design, Cesme, Turkey}, doi = {10.1109/DSD.2012.110}, pages = {84 -- 89}, abstract = {This paper presents the reliability evaluation of task execution during safe software processing. The standard method of duplication in a safety-critical application can also be applied for tasks in a software system. But in addition to this, there is also the possibility for coded task processing to increase the reliability and availability of software. The presented analysis covers the reliability analysis of a single, a duplicated and a coded task by the technique of continuous time Markov processes. Markov processes are often used for the reliability evaluation of safety-critical systems. We introduce a method to describe the execution time of tasks by means of enhanced Markov models and their solution by numerical methods.}, language = {en} } @misc{RueckMatysikBierl, author = {R{\"u}ck, Thomas and Matysik, Frank-Michael and Bierl, Rudolf}, title = {Comparison of acoustic detectors for use in miniaturized photoacoustic devices designed for nitrogen dioxide trace gas measurement}, series = {ANAKON, 23.-26.3.2015, Graz}, journal = {ANAKON, 23.-26.3.2015, Graz}, language = {en} } @inproceedings{SchummJosephSchrollDeckeretal., author = {Schumm, Michael and Joseph, Saskia and Schroll-Decker, Irmgard and Niemetz, Michael and Mottok, J{\"u}rgen}, title = {Required competences in software engineering - pair programming as an instrument for facilitating life-long learning}, series = {15th International Conference on Interactive Collaborative Learning and 41st International Conference on Engineering Pedagogy, Villach}, booktitle = {15th International Conference on Interactive Collaborative Learning and 41st International Conference on Engineering Pedagogy, Villach}, doi = {10.1109/ICL.2012.6402229}, abstract = {The professional requirements in software engineering have become highly volatile due to the complexities of project development and rapid and innovative changes occurring in the field. Therefore, the development of inter-personal and social competences has gained central importance in the training of software developers. The following text will present a concept allowing to acquire competences by using Pair Programming as an instrument. Moreover, arrangements for learning and teaching will be presented facilitating the acquisition of these competences. By approaching the issue of competence acquisition on a technical as well as on an educational and social level, lifelong learning is facilitated and supported.}, language = {en} } @misc{WeiglMatysikBierl, author = {Weigl, Stefan and Matysik, Frank-Michael and Bierl, Rudolf}, title = {Development of a sensor system for analysis of human breath exhale}, series = {BayWISS Herbstakademie 2018, Plankstetten}, journal = {BayWISS Herbstakademie 2018, Plankstetten}, abstract = {Atemgasanalyse ist ein junges und vielversprechendes Feld im Bereich der diagnostischen Medizin. Der Ansatz verspricht einfach zug{\"a}ngliche und leicht wiederholbare Probennahme die zum einen non-invasiv ist und zugleich R{\"u}ckschl{\"u}sse auf Vorg{\"a}nge im menschlichen K{\"o}rper und bspw. dessen Gesundheitszustand zul{\"a}sst. Seit Ende des 20. Jahrhunderts gibt es Massenspektrometer die es erm{\"o}glicht haben mehrere Tausend verschiedene Stoffe in der Ausatemluft nachzuweisen. Diese Technologien verbessern sich stetig und erm{\"o}glichen es die Vorg{\"a}nge und Zusammenh{\"a}nge zwischen Zusammensetzung der Ausatemluft und systemischen Prozessen besser zu verstehen. Die bei Studien mit Massenspektrometern ermittelten Biomarker, deren qualitative und quantitative Detektion Gesundheitsdiagnosen erm{\"o}glichen, haben aber noch nicht den Weg in den klinischen Alltag gefunden. Das Problem sind meistens die hohen Anschaffungskosten, komplizierte Datenauswertung und zumeist geringe Verf{\"u}gbarkeit und Immobilit{\"a}t dieser Messger{\"a}te. Die photoakustische Spektroskopie ist eine selektive und hochsensitive Messmethode, die es erm{\"o}glichen soll den Biomarker „Aceton", der grunds{\"a}tzlich die Metabolisierung von Fetten widerspiegelt, schnell und reproduzierbar quantitativ zu detektieren. Dabei m{\"u}ssen Hindernisse wie Querempfindlichkeiten, ausgel{\"o}st durch die komplexe Zusammensetzung der Messmatrix Atemgas, bei gleichzeitig kleine Aceton Konzentrationen (200-800 parts-per-billion) {\"u}berwunden werden. Verschiedene Wellenl{\"a}ngenbereiche mit unterschiedlichen Lichtquellen, akustisch resonante sowie innovative Messzellendesigns und anspruchsvolle Datenauswertung mittels komplexer Algorithmik sind n{\"o}tig um das Ziel, die Entwicklung eines kompakten, g{\"u}nstigen und zuverl{\"a}ssigen Acetonsensors, zu erreichen.}, language = {en} } @article{RueckBierlMatysik, author = {R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Low-cost photoacoustic NO2 trace gas monitoring at the pptV-level}, series = {Sensors and Actuators A: Physical}, volume = {263}, journal = {Sensors and Actuators A: Physical}, publisher = {Elsevier}, address = {Amsterdam, Niederlande}, doi = {10.1016/j.sna.2017.06.036}, pages = {501 -- 509}, abstract = {We present the development and the characterization of a photoacoustic NO2 trace gas detection system. The system is based on the implementation of low-cost components, i.e. a mass-produced blue diode laser and a standard MEMS microphone which is commonly built into smartphones, for example. An optimized cell design was realized by means of 3D printing. The linearity of the photoacoustic signal dependency on the analyte concentration was verified from 200 ppbV to 100 ppmV NO2. The detection limit (1σ) was determined to 33 pptV and the normalized noise equivalent absorption coefficient was calculated to 7.0 ∙ 10-10 W cm-1 Hz-1/2. The dynamic range of the system was verified to be linear over three magnitudes of order and the sensitivity was calculated to 814 μV/ppmV. The system was characterized in view of optimal operating parameters, i.e. lock-in time constant τLIA and total mass flow rate, optical performance and signal stability. The mass flow dependend response time of the system was specified to 19 s and an idealized step response to a quasi-Heaviside step function was quantified as a function of τLIA. The quality factor of acoustic resonance was determined to 21.9 and an empirical expression regarding acoustic node shifting is provided. The expression takes into account the radius of the resonator pipe and the radius of the hole, which was drilled into the pipe for microphone coupling. Furthermore, we studied the cross-sensitivity of the photoacoustic signal towards H2O and CO2, respectively.}, language = {en} } @article{RueckBierlMatysik, author = {R{\"u}ck, Thomas and Bierl, Rudolf and Matysik, Frank-Michael}, title = {NO2 trace gas monitoring in air using off-beam quartz enhanced photoacoustic spectroscopy (QEPAS) and interference studies towards CO2, H2O and acoustic noise}, series = {Sensors and Actuators B: Chemical}, volume = {255}, journal = {Sensors and Actuators B: Chemical}, number = {Part 3, February}, publisher = {Elsevier}, doi = {10.1016/j.snb.2017.09.039}, pages = {2462 -- 2471}, abstract = {We present the development and characterization as well as comprehensive interference studies of a photoacoustic NO2 trace gas detection system. The system is based on an off-beam quartz enhanced photoacoustic scheme (off-beam QEPAS) and signal generation was initiated by amplitude modulating a low-cost diode laser emitting at 450 nm. The QEPAS sensor element features double-resonant amplification, still it is only ∼ 5 × 5 × 2.5 mm in size. The individual and combined resonance characteristics were investigated and specified to 52 dB amplification, adding up 15 dB acoustic- and 37 dB mechanical-resonance amplification. The linearity of the photoacoustic signal dependency on the analyte concentration was verified from 200 ppbV to 100 ppmV NO2 in synthetic air. The detection limit (3σ) was determined to 1.8 ppbV using a lock-in time constant of 10 s and an averaging time of 20 s. The normalized noise equivalent absorption coefficient was specified to 2.5·10-8 W cm-1 Hz-0.5. The stability of the signal was investigated over time and a slight drift by 1 per mille was observed after 30 min without temperature stabilizing the photoacoustic cell (PAC). Noise analysis was performed by means of Allan deviation and the inverse dependency of response time and precision of the system on the lock-in time constant was outlined. We performed interference analyses towards N2, O2, CO2, H2O and acoustic noise, respectively. Although neither spectral interferences nor losses due to slow NO2 VT-relaxation were observed, O2 was identified to cause a 15\% signal drop due to VVNO2-O2-relaxation. Changing H2O concentrations were found to cause acoustic detuning, which cannot be compensated by adjusting the frequency of modulation, because of the double-resonant feature of the PAC. However, alternative approaches of compensation were discussed. Finally, we carried out heavy traffic noise simulations and determined the QEPAS setup to be 46 times less susceptible towards ambient noise compared to standard microphone-based photoacoustic setups.}, language = {en} } @inproceedings{HauslerWunderlichFischeretal., author = {Hausler, Peter and Wunderlich, Lukas and Fischer, Johannes and Pfab, Christina and Heckscher, Simon and Hirsch, Thomas and Bierl, Rudolf}, title = {Surface plasmon resonance imaging for detection of drug metabolites in water}, series = {Proceedings of SPIE, Optical Sensors 2019, 1 - 4 April 2019, Prague, Czech Republic}, volume = {Vol. 11028}, booktitle = {Proceedings of SPIE, Optical Sensors 2019, 1 - 4 April 2019, Prague, Czech Republic}, issn = {0277-786X}, doi = {10.1117/12.2522324}, pages = {11}, abstract = {The analysis of surface water, groundwater, drinking water as well as sewage is important to get information about the contamination of the water cycle. Currently, these time-consuming investigations require special equipment, like for example hyphenated mass spectrometry. Surface plasmon resonance (SPR) is a faster alternative as it is highly sensitive to changes in the dielectric medium next to a thin metal layer and makes it a quasi-universal detector. Therefore, and due to the labelfree nature, SPR is a widely used sensing tool for real-time monitoring of molecular interactions of various analytes. SPR imaging (SPRi) has several advantages to standard surface plasmon resonance, as it allows to observe many analytes in parallel as well as the integration of referencing technologies. However, the homogenous illumination of a large area (several millimeters) with a small light source is challenging and demands new approaches. Allopurinol, a drug used to lower the blood concentration of urate and hence decrease the affection of gout, gets metabolized to oxipurinol in the body and dropped out almost entirely by urinary excretion. After wastewater treatment, concentrations of oxipurinol up to 21.7 μg•L-1 are detected. Further tracking of oxipurinol in the urban water cycle showed its presence in rivers and streams or even in groundwater. Therefore, the high biological stability of oxipurinol allows this molecule to be used as a marker for domestic wastewater in the environment. For the detection of oxipurinol by SPR graphene was used as receptive layer, as the analyte can bind via π-stacking to this surface. An SPRi technique was developed and compared to conventional SPR system for the detection of oxipurinol.}, language = {en} } @article{WeiglFeldmeierBierletal., author = {Weigl, Stefan and Feldmeier, Florian and Bierl, Rudolf and Matysik, Frank-Michael}, title = {Photoacoustic detection of acetone in N2 and synthetic air using a high power UV LED}, series = {Sensors Actuators B Chemical}, volume = {316}, journal = {Sensors Actuators B Chemical}, number = {August}, publisher = {Elsevier}, doi = {10.1016/j.snb.2020.128109}, pages = {1 -- 11}, abstract = {The performance of a photoacoustic trace gas sensor for the detection of acetone in N2 and synthetic air is reported. The sensor system utilises an amplitude modulated UV LED. The light source has an emission maximum at 278 nm and a maximum CW output power of 300 mW according to the datasheet. Three different collimating and focusing approaches have been investigated to guide the highly divergent LED light into the acoustic resonator of the photoacoustic measurement cell. A 3D printed aluminium cell was designed to optimize light coupling by simultaneously minimizing the photoacoustic background signal generation. Hence, the diameter of the resonator was set to a comparable large diameter of 10 mm and the inner walls of the resonator were mirror polished. The additive manufacturing procedure allowed for integration of a spirally formed gas channel, enabling gas heating prior to detection. The sensor performance was investigated by measuring acetone in N2 and synthetic air at different concentrations. The UV LED current was set to 86 \% of the maximum value according to the datasheet of the light source in order to increase the lifetime and thermal stability. An Allan-Werle deviation analysis validates a stable sensor performance. The limit of detection (LoD) was determined at a 3σ noise level with a 10 s lock-in amplifier time constant by sampling data points over 20 s with a data acquisition rate of 5 Hz. LoDs of 80.8 ppbV and 19.6 ppbV were obtained for acetone in N2 and synthetic air, respectively.}, language = {en} } @inproceedings{HauslerGensleinRothetal., author = {Hausler, Peter and Genslein, Christa and Roth, Carina and Vitzthumecker, Thomas and Hirsch, Thomas and Bierl, Rudolf}, title = {Miniaturized Surface Plasmon Resonance based Sensor System}, series = {Proceedings of the 6th International Conference on Photonics, Optics and Laser Technology - PHOTOPTICS, Funchal, Madeira, Portugal}, booktitle = {Proceedings of the 6th International Conference on Photonics, Optics and Laser Technology - PHOTOPTICS, Funchal, Madeira, Portugal}, publisher = {SciTePress}, isbn = {978-989-758-286-8}, doi = {10.5220/0006555400630066}, pages = {63 -- 66}, abstract = {We describe the miniaturization of the Surface Plasmon Resonance (SPR) technology which mainly finds its applications in pharmaceutical screening and biotechnology so far. SPR spectroscopy is a label-free, non-destructive and highly sensitive measurement principle detecting changes in the refractive index in striking distance to a gold surface. A transfer of this technology to a miniaturized sensor will broaden the range of possible applications. A promising feature which is included in the miniaturized system is the angle-dependent recording of the SPR signals without moving parts. Commercial SPR assays are mainly working with a small number of sensing spots. In contrast, the SPR imaging system shown here will allow to use an array of many sensing spots. In combination with chemical receptors designed as an artificial nose, the simultaneous detection of many analytes is envisioned for future applications.}, language = {en} } @article{BiekerRoustaieSchlaaketal., author = {Bieker, Johannes and Roustaie, Farough and Schlaak, Helmut F. and Langer, Christoph and Schreiner, Rupert and Lotz, Marcel and Wilfert, Stefan}, title = {Field emission characterization of in situ deposited gold nanocones with variable cone densities}, series = {Journal of Vacuum Science and Technology B}, volume = {36}, journal = {Journal of Vacuum Science and Technology B}, number = {2}, publisher = {AIP Publishing}, doi = {10.1116/1.5009504}, abstract = {For the fabrication of field emitter cathodes with metallic nanocones, an in situ fabrication technique based on electrodeposition in an ion track etched polymer template was used. Three samples with nanocones made of gold and different cone densities were deposited on a circular electrode with a diameter of 2.5 mm, using templates with pore density of 6 × 104, 4 × 105, and 1 × 106 cones/cm2. The cones had a height of 24 μm, a base diameter between 3 and 3.75 μm, and a tip diameter below 500 nm. Integral field emission measurements revealed onset fields of down to 3.1 V/μm and average field enhancement factors of up to 1240. For one sample, the maximum emission current from the cathode reached 142.2 μA at an applied voltage of 338 V between cathode and extraction grid, which had a distance of 50 μm. To investigate the stability of the field emission current, cumulative long-term measurements were performed for over 50 h. A stable emission current of (31.0 ± 1.3) μA at an average applied voltage of 290 V (E = 5.8 V/μm) was observed. For currents above 100 μA, a decrease of the current and therefore a degradation of the emitter structures occurred.}, language = {en} } @inproceedings{Mottok, author = {Mottok, J{\"u}rgen}, title = {Embedded trends}, series = {Technologietag 2012, am 28. M{\"a}rz, M{\"u}nchen}, booktitle = {Technologietag 2012, am 28. M{\"a}rz, M{\"u}nchen}, language = {en} }