TY - JOUR A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Lechner, Alfred A1 - Graf, Antonia A1 - Dams, Florian A1 - Schreiner, Rupert A1 - Auchter, Eberhard A1 - Kriz, Willy A1 - Deubzer, MIchael A1 - Schiller, Frank A1 - Mottok, Jürgen A1 - Niemetz, Michael A1 - Margull, Ulrich A1 - Hagel, Georg A1 - Utesch, Matthias A1 - Waldherr, Franz A1 - Böhm, Matthias A1 - Fraunhoffer, Judith A1 - Gardeia, Armin A1 - Schneider, Ralph A1 - Streubel, Janet A1 - Landes, Dieter A1 - Studt, Reimer A1 - Peuker, Dominik A1 - Scharfenberg, Georg A1 - Hook, Christian A1 - Schuster, Dietwald A1 - Ehrlich, Ingo A1 - Dinnebier, Heinrich A1 - Briem, Ulrich A1 - Lämmlein, Stephan A1 - Koder, Alexander A1 - Bialek, Adam A1 - Genewsky, Axel A1 - Neumeier, Michael A1 - Schlosser, Philipp A1 - Rabl, Hans-Peter A1 - Paule, Matthias A1 - Galster, Christoph A1 - Schiedermeier, Michael A1 - Zwickel, Andreas A1 - Hobmeier, Christoph A1 - Bischoff, Tobias A1 - Rill, Georg A1 - Schaeffer, Thomas A1 - Arbesmeier, Martin A1 - Groß, Andreas A1 - Schlegl, Thomas A1 - Becker, Mark A1 - Senn, Konrad A1 - Schliekmann, Claus A1 - Scholz, Peter A1 - Sippl, Christian A1 - Grill, Martin ED - Eckstein, Josef T1 - Forschungsbericht 2011 / Hochschule für Angewandte Wissenschaften - Fachhochschule Regensburg T3 - Forschungsberichte der OTH Regensburg - 2011 Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-7321 SN - 1868-3533 CY - Regensburg ER - TY - JOUR A1 - Pangerl, Jonas A1 - Müller, Max A1 - Rück, Thomas A1 - Weigl, Stefan A1 - Bierl, Rudolf T1 - Characterizing a sensitive compact mid-infrared photoacoustic sensor for methane, ethane and acetylene detection considering changing ambient parameters and bulk composition (N2, O2 and H2O) JF - Sensors and Actuators B: Chemical N2 - We present a sensitive and compact interband cascade laser (ICL) based photoacoustic setup for the detection of gaseous hydrocarbons and discuss its applicability towards trace gas analysis. We investigated the performance of the sensor for trace concentrations of methane, ethane and acetylene diluted in nitrogen. The excitation of methane and ethane was accomplished using one tunable diode laser, covering a range from 3360 to 3372 nm, which was replaced by a separate ICL at 3025 nm for acetylene detection. The influence of ambient parameters such as temperature, flow rate and pressure as well as potential cross-sensitivities towards O2 and H2O have been examined in terms of methane and acetylene detection. A series of simulations proved several of these influences to be attributed to relaxation effects. With a 3σ limit of detection (LoD) of 6.8 parts per billion (ppbV) in case of methane, 2.3 ppbV regarding ethane and 3.6 ppbV in terms of acetylene, the sensor demonstrates a great potential for applications in the field of trace gas analysis. KW - Acetylene KW - Cross-sensitivities KW - Ethane KW - Interband cascade laser KW - Methane KW - Photoacoustic spectroscopy KW - Relaxation effects Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-25868 N1 - Corresponding author: Jonas Pangerl VL - 352,1 SP - 1 EP - 12 PB - Elsevier ER - TY - JOUR A1 - Müller, Max A1 - Rück, Thomas A1 - Jobst, Simon A1 - Pangerl, Jonas A1 - Weigl, Stefan A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - An Algorithmic Approach to Compute the Effect of Non-Radiative Relaxation Processes in Photoacoustic Spectroscopy JF - Photoacoustics N2 - Successful transfer of photoacoustic gas sensors from laboratory to real-life applications requires knowledge about potential cross-sensitivities towards environmental and gas matrix changes. Multi-dimensional calibration in case of cross-sensitivities can become very complex or even unfeasible. To address this challenge, we present a novel algorithm to compute the collision based non-radiative efficiency and phase lag of energy relaxation on a molecular level (CoNRad) for photoacoustic signal calculation. This algorithmic approach allows to calculate the entire elaxation cascade of arbitrarily complex systems, yielding a theoretical photoacoustic signal. In this work the influence of varying bulk compositions, i.e. nitrogen (N2), oxygen (O2) and water (H2O) on the photoacoustic signal during methane (CH4) detection is demonstrated. The applicability of the algorithm to other photoacoustic setups is shown exemplary by applying it to the relaxational system investigated in [1]. Hayden et al. examined the effect of water on photoacoustic carbon monoxide (CO) detection. Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-39935 N1 - Corresponding author: Max Müller VL - 26 PB - Elsevier ER - TY - GEN A1 - Rück, Thomas A1 - Hofmann, Matthias A1 - Bierl, Rudolf T1 - Development of a miniaturized photoacoustic multigas sensing system for trace gas measurement T2 - 17th International Conference on Photoacoustic and Photothermal Phenomena, Oct. 20-24, 2013, Suzhou China Y1 - 2013 UR - https://www.gdch.de/fileadmin/downloads/Veranstaltungen/Tagungen/2014_Tagungen/analytica/poster_abstracts/sens05_rueck_5925.pdf ER - TY - GEN A1 - Rück, Thomas A1 - Matysik, Frank-Michael A1 - Bierl, Rudolf T1 - Development of a miniaturized photoacoustic multigas sensing system for trace gas measurement T2 - analytica conference 2014, 1. bis 4. April, München Y1 - 2014 UR - https://www.gdch.de/fileadmin/downloads/Veranstaltungen/Tagungen/2014_Tagungen/analytica/poster_abstracts/sens05_rueck_5925.pdf ER - TY - GEN A1 - Rück, Thomas A1 - Matysik, Frank-Michael A1 - Bierl, Rudolf T1 - Comparison of acoustic detectors for use in miniaturized photoacoustic devices designed for nitrogen dioxide trace gas measurement T2 - ANAKON, 23.-26.3.2015, Graz Y1 - 2015 ER - TY - JOUR A1 - Pangerl, Jonas A1 - Sukul, Pritam A1 - Rück, Thomas A1 - Fuchs, Patricia A1 - Weigl, Stefan A1 - Miekisch, Wolfram A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - An inexpensive UV-LED photoacoustic based real-time sensor-system detecting exhaled trace-acetone JF - Photoacoustics N2 - n this research we present a low-cost system for breath acetone analysis based on UV-LED photoacoustic spectroscopy. We considered the end-tidal phase of exhalation, which represents the systemic concentrations of volatile organic compounds (VOCs) – providing clinically relevant information about the human health. This is achieved via the development of a CO2-triggered breath sampling system, which collected alveolar breath over several minutes in sterile and inert containers. A real-time mass spectrometer is coupled to serve as a reference device for calibration measurements and subsequent breath analysis. The new sensor system provided a 3σ detection limit of 8.3 ppbV and an NNEA of 1.4E-9 Wcm 1Hz 0.5. In terms of the performed breath analysis measurements, 12 out of 13 fell within the error margin of the photoacoustic measurement system, demonstrating the reliability of the measurements in the field. KW - Photoacoustic spectroscopy KW - Real-time mass-spectrometry KW - Breath analysis KW - Acetone KW - UV-LED Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-71279 SN - 2213-5979 N1 - Corresponding author der OTH Regensburg: Jonas Pangerl VL - 38 PB - Elsevier ER - TY - JOUR A1 - Escher, Lukas A1 - Rück, Thomas A1 - Jobst, Simon A1 - Pangerl, Jonas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Photodissociation-Driven Photoacoustic Spectroscopy with UV-LEDs for Ozone Detection JF - Photoacoustics N2 - This study presents the development and evaluation of a UV-LED based photoacoustic (PA) measurement system for ozone (O3) detection to demonstrate its potential for low-cost and accurate sensing while for the first time addressing the importance of photodissociation for PA signal generation for O3 in the UV range. With a detection limit of 7.9 ppbV, the system exhibits a significant advancement over state-of-the-art UV-PA O3 detection and is on par with laser-based setups. Following a novel discussion of the PA signal arising from photodissociation and its products, cross-sensitivity effects due to environmental factors such as temperature and gas composition were systematically analyzed. A digital twin driven compensation for these influences was implemented and evaluated. Despite the challenges associated with modeling the effects of H2O and CO2, the PA system shows considerable potential, though further studies in real world applications must be conducted. KW - Photoacoustic spectroscopy KW - UV-LED KW - Ozone KW - Photodissociation KW - Cross-sensitivity Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-80076 SN - 2213-5979 N1 - Corresponding author der OTH Regensburg: Lukas Escher VL - 43 PB - Elsevier BV ER - TY - JOUR A1 - Weigl, Stefan A1 - Wittmann, Elisabeth A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Effects of ambient parameters and cross-sensitivities from O2, CO2 and H2O on the photoacoustic detection of acetone in the UV region JF - Sensors Actuators B Chemical N2 - We present a sensitive UV LED photoacoustic setup for the detection of gaseous acetone and discuss its applicability towards breath analysis. We investigated the performance of the sensor for low acetone concentrations down to 0.1 parts per million (ppmV). The influences of temperature, flow, pressure, optical power and LED duty cycle on the measured signal have been examined. To gain a better understanding of the different effects on the photoacoustic signal, correlation analysis was applied and feature importance was determined using a large measured dataset. Furthermore, the cross-sensitivities towards O2, CO2 and H2O have been studied extensively. Finally, the sensor’s performance to detect acetone between 0.1–1 ppmV within gas mixtures simulating breath exhale conditions has been investigated, too. With a limit of detection (LoD) of 12.5 parts per billion (ppbV) (3σ) measured under typical breath exhale gas mixture conditions, the sensor demonstrated a high potential for the application of acetone detection in human breath analysis. KW - Acetone detection KW - Photoacoustic spectroscopy KW - High power UV LED KW - Cross-sensitivities KW - Acetone breath analysis Y1 - 2021 U6 - https://doi.org/10.1016/j.snb.2020.129001 SN - 0925-4005 N1 - Corresponding authors: Stefan Weigl, Elisabeth Wittmann, Thomas Rück, Rudolf Bierl, Frank-Michael Matysik N1 - Corrigendum to “Effects of ambient parameters and cross-sensitivities from O2, CO2 and H2O on the photoacoustic detection of acetone in the UV region” [Sens. Actuators B: Chem. 328 (February 2021) (2020) 129001]; https://doi.org/10.1016/j.snb.2020.129392 IS - 328 PB - Elsevier ER - TY - INPR A1 - Pangerl, Jonas A1 - Sukul, Pritam A1 - Rück, Thomas A1 - Fuchs, Patricia A1 - Weigl, Stefan A1 - Miekisch, Wolfram A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - An Inexpensive Uv-Led Photoacoustic Based Real-Time Sensor-System Detecting Exhaled Trace-Acetone N2 - In this research we present a low-cost system for breath acetone analysis based on UV-LED photoacoustic spectroscopy. We considered the end-tidal phase of exhalation, which represents the systemic concentrations of volatile organic compounds (VOCs) – providing clinically relevant information about the human health. This is achieved via the development of a CO2-triggered breath sampling system, which collected alveolar breath over several minutes in sterile and inert containers. A real-time mass spectrometer is coupled to serve as a reference device for calibration measurements and subsequent breath analysis. The new sensor system provided a 3σ detection limit of 6.4 ppbV and an NNEA of 1.1E-9 Wcm-1Hz-0.5. In terms of the performed breath analysis measurements, 12 out of 13 fell within the error margin of the photoacoustic measurement system, demonstrating the reliability of the measurements in the field. KW - photoacoustic spectroscopy KW - real-time mass-spectrometry KW - breath analysis KW - acetone KW - UV-LED Y1 - 2024 U6 - https://doi.org/10.2139/ssrn.4724198 N1 - Der Aufsatz wurde peer-reviewed unter folgender DOI veröffentlicht: https://doi.org/10.1016/j.pacs.2024.100604 PB - Elsevier ER - TY - JOUR A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - NO2 trace gas monitoring in air using off-beam quartz enhanced photoacoustic spectroscopy (QEPAS) and interference studies towards CO2, H2O and acoustic noise JF - Sensors and Actuators B: Chemical N2 - 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‰ 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. Y1 - 2018 U6 - https://doi.org/10.1016/j.snb.2017.09.039 VL - 255 IS - Part 3, February SP - 2462 EP - 2471 PB - Elsevier ER - TY - JOUR A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Development and characterization of a laboratory setup for photoacoustic NO2 determination based on the excitation of electronic 2B2 and 2B1 states using a low-cost semiconductor laser JF - Sensors and Actuators A: Physical N2 - This work gives a detailed characterization of a laboratory setup for photoacoustic NO2 trace gas detection at the ppb level. The signal generation is based on the excitation of electronic 2B2 and 2B1 states using a low-cost semiconductor laser emitting at 450 nm. An acoustic resonator was used for signal amplification and the modulation frequency of the laser was determined to 3395 Hz in order to gain maximum signal amplification. The quality of resonant amplification was determined to 7.9. The gas samples were NO2 calibration gases diluted with pure nitrogen. The signal-to-noise ratio (SNR) dependency on the flow rate Q and the lock-in time constant τLIA was investigated, respectively, and the optimum values were specified to Q = 500 mL/min and τLIA = 2 s. In case of ambient noise, increasing τLIA to 10 s was evaluated as sufficient for SNR preservation. The noise level was measured in the absence of NO2 and it was determined to be composed of 51% electronic noise and 49% gas flow noise. With the analyte concentration ranging from 300 ppbV to 100 ppmV, the linear dependency of the photoacoustic amplitude on the NO2 concentration was specified, the sensitivity was determined to 110 μV/ppmV and the maximum measurement error was calculated to ±0.8%. The detection limit was determined to 2.0 ppbV. Furthermore, the stability of the signal was investigated and a maximum drift of ±1% was observed within a measuring period of 30 min. The response time τ90 was specified to 58 s. All results considered, this photoacoustic measuring system, which is based on low-cost signal generation and detection units, provides an excellent basis in view of developing a portable device for photoacoustic trace gas detection. Y1 - 2017 U6 - https://doi.org/10.1016/j.sna.2017.03.024 VL - 258 SP - 193 EP - 200 PB - Elsevier CY - Amsterdam, Niederlande ER - TY - JOUR A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Low-cost photoacoustic NO2 trace gas monitoring at the pptV-level JF - Sensors and Actuators A: Physical N2 - 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. Y1 - 2017 U6 - https://doi.org/10.1016/j.sna.2017.06.036 VL - 263 SP - 501 EP - 509 PB - Elsevier CY - Amsterdam, Niederlande ER - TY - CHAP A1 - Zhou, Qi A1 - Landgraf, Ferdinand A1 - Rück, Thomas A1 - Bierl, Rudolf T1 - Resonance frequency tuning and process design of a micromechanical capacitive cantilever in a photoacoustic trace-gas sensing device T2 - 7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, München N2 - Photoacoustic spectroscopy is an efficient method to detect the concentration of trace gases with following advantages: short response time, high sensitivity, continuous and real-time monitoring and the option of miniaturization without the need of complex mirror-based multi-pass cell designs. A micromechanical cantilever is used as a key component in a two-part "Cantilever-Resonator" system that detects the weak photoacoustic signal. The resonance frequency of cantilever needs to be tuned to match the resonance frequency of resonator in order to achieve the maximum vibration amplitude of the "Cantilever-Resonator" system. This paper reports a post-fabrication method to tune the resonance frequency of cantilevers via focused ion beam (FIB) and a capacitive solution for the cantilever to transform the acoustic signal to electrical signal. Y1 - 2017 SN - 978-3-8007-4491-6 PB - VDE-Verlag CY - Berlin ER - TY - CHAP A1 - Rück, Thomas A1 - Läpple, I. A1 - Bierl, Rudolf T1 - Photoakustische Spurengasanalytik von NO2 im ppt-Bereich (10^-12) bei Verwendung kostengünstiger Einzelkomponenten T2 - 7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, München KW - Elektroniksystem KW - Industrie 4.0 KW - Mikrosystemtechnik KW - Mikrofluidik KW - Mikroaktorik Y1 - 2017 SN - 978-3-8007-4491-6 PB - VDE-Verlag CY - Berlin ER - TY - JOUR A1 - Zagler, Andreas A1 - Landgraf, Ferdinand A1 - Rück, Thomas A1 - Bierl, Rudolf T1 - Entwicklung eines mikromechanischen kapazitiven Schalldetektors im resonanten Betrieb für die photoakustische Spurengasanalyse JF - 7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, München Y1 - 2017 PB - VDE-Verlag CY - Berlin ER - TY - CHAP A1 - Gaida, Peter A1 - Weigl, Stefan A1 - Rück, Thomas A1 - Bierl, Rudolf T1 - Portable photoakustische Messeinheit zur NO2 Detektion im Spurenbereich T2 - 7. MikroSystemTechnik Kongress "MEMS, Mikroelektronik, Systeme", 23.-25. Oktober 2017, München Y1 - 2017 SN - 978-3-8007-4491-6 PB - VDE-Verlag CY - Berlin ER - TY - CHAP A1 - Weigl, Stefan A1 - Gaida, Peter A1 - Rück, Thomas A1 - Bierl, Rudolf T1 - Portable Measurement Unit for NO2 Trace Gas Detection T2 - PHOTOPTICS 2018, 6th International Conference on Photonics, Optics and Laser Technology, 25 - 27 January 2018, Funchal Madeira Y1 - 2018 ER - TY - RPRT A1 - Unger, J. A1 - Rück, Thomas A1 - Landgraf, Ferdinand A1 - Bierl, Rudolf T1 - Herstellung und Analyse der Resonanzfrequenz eines MEMS Cantilever für das CEPAS Verfahren N2 - Diese Abhandlung beschreibt das Konzept eines mikroeletromechanischen Systems (MEMS), das im Messverfahren der cantilever enhanced photoacoustic spectroscopy (CEPAS) Verwendung finden soll. Es wird die Herstellung eines einseitig eingespannten Biegebalkens aus Silizium mittels deep reactiv ion etching (DRIE) beschrieben. Des Weiteren wird die Resonanzfrequenz dieses Cantilevers mit Hilfe Laservibrometertechnik untersucht. Die resultierenden resonanten Schwingungen 0.Ordnung werden mit den Ergebnissen einer vereinfachten theoretischen Näherung verglichen. Die Messergebnisse stehen in gutem Zusammenhang mit den theoretischen Werten. Solche Cantilever, die aus silicon on insula tor (SOI) Wafer angefertigt wurden, weisen bei einer Zielfrequenz ein mittlere Abweichung von Δf = 118±26Hz (bzw.Δf =0,76±0,17%) auf. Y1 - 2015 ER - TY - CHAP A1 - Hofmann, Matthias A1 - Bierl, Rudolf A1 - Rück, Thomas T1 - Implementation of a dual-phase lock-in amplifier on a TMS320C5515 digital signal processor T2 - Proceedings of the 5th European DSP Education and Research Conference (EDERC), 13-14 Sept. 2012, Amsterdam N2 - A digital dual-phase lock-in amplifier that is capable to run on a low-cost, low-power platform comprising a 16-bit fixed-point digital signal processor was developed. This is achieved by a set of optimised digital filters including an exponential averager to adjust the time constant of the overall filter. The reference frequency is generated using a direct digital synthesis source utilising angle decomposition with a resolution of 1 Hz. The digital lock-in algorithm is described and the performance of the algorithm is analysed. The experimental results show that the developed lock-in amplifier achieves similar performance to a commercially available lock-in amplifier. Y1 - 2012 U6 - https://doi.org/10.1109/EDERC.2012.6532217 ER - TY - CHAP A1 - Rück, Thomas A1 - Landgraf, Ferdinand A1 - Läpple, I. A1 - Unger, J. A1 - Matysik, Frank-Michael A1 - Bierl, Rudolf T1 - Specification of an improved photoacoustic setup for high-sensitive, low-cost NO2 trace gas detection T2 - 18th International Conference on Photoacoustic and Photothermal Phenomena (ICPPP18), 2015, September 6-10, Novi Sad, Serbia Y1 - 2015 ER - TY - INPR A1 - Rück, Thomas A1 - Müller, Max A1 - Jobst, Simon A1 - Weigl, Stefan A1 - Pangerl, Jonas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Digital Twin of a Photoacoustic Trace Gas Sensor for Monitoring Methane in Complex Gas Compositions N2 - The digitalization of industrial processes requires smart sensor systems. Photoacoustic spectroscopy is well suited for this purpose as it allows for small-sized and low-cost trace gas analysis. However, the method is susceptible to changes in measurement conditions and standard calibration routines often fail to correct for all changes. We therefore created a Digital Twin (DT) of a photoacoustic trace gas sensor for methane and evaluated it regarding variations in gas composition (CH4, N2, O2, CO2, H2O), temperature and pressure. With a mean absolute percentage error of 0.8 % the accuracy of the sensor after DT compensation significantly exceeds the 24 % achieved based on standard calibration in nitrogen. For the first time, we can fully analytically compute the photoacoustic signal under moderate ambient conditions with an error in the ppbV range by taking a holistic approach. Assuming knowledge of the underlying energy transfer processes, the model of this Digital Twin can be adapted to any microphone based photoacoustic sensor for monitoring any analyte species. Y1 - 2022 U6 - https://doi.org/10.2139/ssrn.4215170 PB - Elsevier / SSRN ER - TY - CHAP A1 - Müller, Max A1 - Rück, Thomas A1 - Jobst, Simon A1 - Pangerl, Jonas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Creating a Digital Twin of a Photoacoustic Gas Sensor for Methane Detection in Complex Gas Matrices T2 - Proceedings Optical Sensors and Sensing Congress 2022 (AIS, LACSEA, Sensors, ES): 11–15 July 2022, Vancouver, British Columbia, Canada N2 - We present the calculation results from a digital twin (DT) of our photoacoustic (PA) sensor for methane detection, regarding gas composition, temperature and pressure variations. Y1 - 2022 SN - 978-1-957171-10-4 U6 - https://doi.org/10.1364/LACSEA.2022.LW4D.2 PB - Optica Publishing Group ER - TY - INPR A1 - Müller, Max A1 - Weigl, Stefan A1 - Müller-Williams, Jennifer A1 - Lindauer, Matthias A1 - Rück, Thomas A1 - Jobst, Simon A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Ambient methane monitoring at Hohenpeißenberg utilizing photoacoustic spectroscopy and cavity ring down spectroscopy N2 - With an atmospheric concentration of approximately 2000 parts per billion (ppbV, 10−9) methane (CH4) is the second most abundant greenhouse gas (GHG) in the atmosphere after carbon dioxide (CO2). The task of long-term and spatially resolved GHG monitoring to verify whether climate policy actions are effective, is becoming more crucial as climate change progresses. In this paper we report the CH4 concentration readings of our photoacoustic (PA) sensor over a five day period at Hohenpeißenberg, Germany. As a reference device a calibrated cavity ringdown spectrometer Picarro G2301 from the meteorological observatory was employed. Trace gas measurements with photoacoustic instruments promise to provide low detection limits at comparably low costs. However, PA devices are often susceptible to cross-sensitivities related to environmental influences. The obtained results show that relaxation effects due to fluctuating environmental conditions, e.g. ambient humidity, are a non-negligible factor in PA sensor systems. Applying algorithm compensation techniques, which are capable of calculating the influence of relaxational effects on the photoacoustic signal, increase the accuracy of the photoacoustic sensor significantly. With an average relative deviation of 1.11 % from the G2301, the photoacoustic sensor shows good agreement with the reference instrument. Y1 - 2023 U6 - https://doi.org/10.5194/egusphere-2023-1010 ER - TY - JOUR A1 - Rück, Thomas A1 - Müller, Max A1 - Jobst, Simon A1 - Weigl, Stefan A1 - Pangerl, Jonas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Digital Twin of a Photoacoustic Trace Gas Sensor for Monitoring Methane in Complex Gas Compositions JF - Sensors and Actuators B: Chemical N2 - The digitalization of industrial processes requires smart sensor systems. Photoacoustic spectroscopy is well suited for this purpose as it allows for small-sized and low-cost trace gas analysis. However, the method is susceptible to changes in measurement conditions and standard calibration routines often fail to correct for all changes. We therefore created a Digital Twin (DT) of a photoacoustic trace gas sensor for methane and evaluated it regarding variations in gas composition (CH4, N2, O2, CO2, H2O), temperature and pressure. With a mean absolute percentage error of 0.8 % the accuracy of the sensor after DT compensation significantly exceeds the 24 % achieved based on standard calibration in nitrogen. For the first time, we can fully analytically compute the photoacoustic signal under moderate ambient conditions with an error in the ppbV range by taking a holistic approach. Assuming knowledge of the underlying energy transfer processes, the model of this Digital Twin can be adapted to any microphone based photoacoustic sensor for monitoring any analyte species. KW - Digital Twin KW - Photoacoustic spectroscopy KW - Smart sensor KW - Acoustic resonance monitoring KW - CoNRad KW - Calibration-free method Y1 - 2023 U6 - https://doi.org/10.1016/j.snb.2022.133119 N1 - Preprint unter: https://doi.org/10.2139/ssrn.4215170 ; https://opus4.kobv.de/opus4-oth-regensburg/frontdoor/index/index/docId/5417 IS - 378 ER - TY - CHAP A1 - Escher, Lukas A1 - Rück, Thomas A1 - Jobst, Simon A1 - König, Martin A1 - Bierl, Rudolf T1 - Design and Characterization of a Low-Cost Photoacoustic Sensor for NO2 Using Lateral Illumination and Background Suppression T2 - Imaging and Applied Optics Congress 2022 (3D, AOA, COSI, ISA, pcAOP): 11–15 July 2022, Vancouver, British Columbia, Canada N2 - We introduce a low-cost photoacoustic NO2 sensor based on lateral LED illumination and optical background signal compensation. The 3σ limit of detection (LOD) was identified to be 24 ppbV. Y1 - 2022 SN - 978-1-957171-09-8 U6 - https://doi.org/10.1364/3D.2022.JTu2A.10 PB - Optica Publishing Group ER - TY - INPR A1 - Pangerl, Jonas A1 - Sukul, Pritam A1 - Rück, Thomas A1 - Escher, Lukas A1 - Miekisch, Wolfram A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Photoacoustic Trace-Analysis of Breath Isoprene and Acetone Via Interband- and Quantum Cascade Lasers N2 - This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the PAS systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm-1Hz-0.5 and 4.9E-9 Wcm-1Hz-0.5. Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices. KW - photoacoustic spectroscopy KW - breath analysis/profiling KW - real-time mass spectroscopy KW - isoprene KW - acetone Y1 - 2024 U6 - https://doi.org/10.2139/ssrn.4834735 PB - Elsevier / SSRN ER - TY - JOUR A1 - Pangerl, Jonas A1 - Sukul, Pritam A1 - Rück, Thomas A1 - Escher, Lukas A1 - Miekisch, Wolfram A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Photoacoustic trace-analysis of breath isoprene and acetone via interband- and Quantum Cascade Lasers JF - Sensors and Actuators: B. Chemical N2 - This research presents two laser-based photoacoustic approaches for analyzing exhaled breath isoprene and acetone. The integration of a PTR-ToF-MS as a reference device ensured the reliability and accuracy of the photoacoustic systems that is based on an ICL for isoprene and a QCL for acetone detection. The calibration yielded limits of detection of 26.9 ppbV and 1.7 ppbV, respectively, and corresponding normalized noise equivalent absorption coefficients (NNEAs) of 5.0E-9 Wcm 1Hz 0.5 and 4.9E-9 Wcm 1Hz 0.5. Laboratory as well as real breath sample measurements from alveolar breath revealed a robust system performance, with only one outlier within the static isoprene measurements. However, discrepancies emerged under dynamic breath sampling conditions, emphasizing the need for further optimization. Especially by knowing the dynamic nature and endogenous origin of exhaled isoprene our findings highlight the potential of breath analysis for non-invasive physio-metabolic and pathophysiological monitoring towards point-of-care devices KW - Photoacoustic spectroscopy KW - Breath analysis/profiling KW - Real-time mass spectrometry KW - Isoprene KW - Acetone Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-77024 N1 - Corresponding author der OTH Regensburg: Jonas Pangerl VL - 424 PB - Elsevier ER - TY - CHAP A1 - Escher, Lukas A1 - Müller, Max A1 - Rück, Thomas A1 - Jobst, Simon A1 - Bierl, Rudolf T1 - Digitaler Zwilling photoakustischer Spurengassensoren zur Prozessüberwachung T2 - 16. Dresdner Sensor-Symposium 2022: Vorträge N2 - Stickstoffdioxid (NO2) wird hauptsächlich durch anthropogene Verbrennungsprozesse in Verkehr und Industrie in die Umgebungsluft eingebracht [1]. Die stark reaktive, oxidative Wirkung von NO2 kann bei Exposition mit höheren Konzentrationen Reizungen und allergische Reaktionen in den Atemwegen hervorrufen. Weiter führt NO2 zur Bildung von saurem Regen, Smog und Ozon (O3) die sich ebenso negativ auf die menschliche Gesundheit und Umwelt auswirken [2,3]. Aufgrund dieser Effekte wird die Spurengaskonzentration von NO2 in der Luft in Deutschland an ausgewählten, verkehrsreichen Orten gemessen. Y1 - 2022 SN - 978-3-9819376-7-1 U6 - https://doi.org/10.5162/16dss2022/3.3 PB - AMA (Association for Sensors + Measurement) ER - TY - JOUR A1 - Rück, Thomas A1 - Pangerl, Jonas A1 - Escher, Lukas A1 - Jobst, Simon A1 - Müller, Max A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Kinetic cooling in mid-infrared methane photoacoustic spectroscopy: A quantitative analysis via digital twin verification JF - Photoacoustics N2 - This study presents a detailed quantitative analysis of kinetic cooling in methane photoacoustic spectroscopy, leveraging the capabilities of a digital twin model. Using a quantum cascade laser tuned to 1210.01 cm⁻¹, we investigated the effects of varying nitrogen-oxygen matrix compositions on the photoacoustic signals of 15 ppmV methane. Notably, the photoacoustic signal amplitude decreased with increasing oxygen concentration, even falling below the background signal at oxygen levels higher than approximately 6 %V. This phenomenon was attributed to kinetic cooling, where thermal energy is extracted from the surrounding gas molecules rather than added, as validated by complex vector analysis using a previously published digital twin model. The model accurately reproduced complex signal patterns through simulations, providing insights into the underlying molecular mechanisms by quantifying individual collision contributions. These findings underscore the importance of digital twins in understanding the fundamentals of photoacoustic signal generation at the molecular level. Y1 - 2024 U6 - https://doi.org/10.1016/j.pacs.2024.100652 VL - 40 PB - Elsevier ER - TY - JOUR A1 - Pangerl, Jonas A1 - Moser, Elisabeth A1 - Müller, Max A1 - Weigl, Stefan A1 - Jobst, Simon A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - A sub-ppbv-level Acetone and Ethanol Quantum Cascade Laser Based Photoacoustic Sensor– Characterization and Multi-Component Spectra Recording in Synthetic Breath JF - Photoacoustics N2 - Trace gas analysis in breath is challenging due to the vast number of different components. We present a highly sensitive quantum cascade laser based photoacoustic setup for breath analysis. Scanning the range between 8263 and 8270 nm with a spectral resolution of 48 pm, we are able to quantify acetone and ethanol within a typical breath matrix containing water and CO2. We photoacoustically acquired spectra within this region of mid-infra-red light and prove that those spectra do not suffer from non-spectral interferences. The purely additive behavior of a breath sample spectrum was verified by comparing it with the independently acquired single component spectra using Pearson and Spearman correlation coefficients. A previously presented simulation approach is improved and an error attribution study is presented. With a 3σ detection limit of 6.5 ppbv in terms of ethanol and 250 pptv regarding acetone, our system is among the best performing presented so far. KW - Acetone KW - Breath analysis KW - Photoacoustic spectroscopy KW - Quantum cascade laser KW - Spectral simulation Y1 - 2023 U6 - https://doi.org/10.1016/j.pacs.2023.100473 SN - 2213-5979 N1 - Corresponding author: Jonas Pangerl VL - 30 SP - 1 EP - 12 PB - Elsevier ER - TY - CHAP A1 - Weigl, Stefan A1 - Müller, Max A1 - Pangerl, Jonas A1 - Rück, Thomas T1 - Scopes and Limits of Photoacoustic Spectroscopy in Modern Breath Analysis T2 - Breath Analysis N2 - Photoacoustic spectroscopy is a viable tool for trace gas detection in various application fields. In recent years, this technique has been exploited more and more for modern breath analysis as well. Within this chapter, a holistic overview of photoacoustic spectroscopy is presented, while maintaining the relationship to breath analysis. Therefore, a concise description of the fundamentals of photoacoustic spectroscopy is provided. This is essential for understanding the scopes and limits of this outstanding measurement technique being described within this chapter. In the past several different types of photoacoustic measurement setups for trace gas detection have emerged, including different light sources, modulation techniques, and detection schemes. These are described shortly and advantages as well as disadvantages, especially in relation to breath analysis, are highlighted. Though being a promising sensor principle, measurement devices based on photoacoustic spectroscopy are still rare on the sensor market, especially when it comes to trace gas detection in complex gas matrices, e.g., human breath exhale. One main reason is due to possible molecular interactions influencing the relaxational behavior of the analyte altering the sensor signal. Recent results shedding light on the intricate relaxational processes within complex gas matrices are discussed in detail, providing approaches to overcome this issue. Finally, various applications of photoacoustic spectroscopy in breath analysis are described demonstrating the great potential of this technology. Y1 - 2022 SN - 978-3-031-18526-7 U6 - https://doi.org/10.1007/11663_2022_22 SP - 101 EP - 159 PB - Springer nature ER - TY - JOUR A1 - Müller, Max A1 - Weigl, Stefan A1 - Müller-Williams, Jennifer A1 - Lindauer, Matthias A1 - Rück, Thomas A1 - Jobst, Simon A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - Comparison of photoacoustic spectroscopy and cavity ring-down spectroscopy for ambient methane monitoring at Hohenpeißenberg JF - Atmospheric Measurement Techniques N2 - With an atmospheric concentration of approximately 2000 parts per billion (ppbV, 10−9), methane (CH4) is the second most abundant greenhouse gas (GHG) in the atmosphere after carbon dioxide (CO2). The task of long-term and spatially resolved GHG monitoring to verify whether climate policy actions are effective is becoming more crucial as climate change progresses. In this paper we report the CH4 concentration readings of our photoacoustic (PA) sensor over a 5 d period at Hohenpeißenberg, Germany. As a reference device, a calibrated cavity ring-down spectrometer, Picarro G2301, from the meteorological observatory of the German Weather Service (DWD) was employed. Trace gas measurements with photoacoustic instruments promise to provide low detection limits at comparably low costs. However, PA devices are often susceptible to cross-sensitivities related to fluctuating environmental conditions, e.g. ambient humidity. The obtained results show that for PA sensor systems non-radiative relaxation effects induced by varying humidity are a non-negligible factor. Applying algorithm compensation techniques, which are capable of calculating the influence of non-radiative relaxation effects on the photoacoustic signal, increase the accuracy of the photoacoustic sensor significantly. With an average relative deviation of 1.11 % from the G2301, the photoacoustic sensor shows good agreement with the reference instrument. Y1 - 2023 U6 - https://doi.org/10.5194/amt-16-4263-2023 SN - 1867-8548 VL - 16 IS - 18 SP - 4263 EP - 4270 PB - Copernicus Publications ER - TY - INPR A1 - Pangerl, Jonas A1 - Moser, Elisabeth A1 - Müller, Max A1 - Weigl, Stefan A1 - Jobst, Simon A1 - Rück, Thomas A1 - Bierl, Rudolf A1 - Matysik, Frank-Michael T1 - A Highly Sensitive Acetone and Ethanol Quantum Cascade Laser Based Photoacoustic Sensor: Characterization and Multi-Component Spectra Recording in Synthetic Breath T2 - SSRN Electronic Journal N2 - Trace gas analysis in breath is challenging due to the vast number of different components. We present a highly sensitive quantum cascade laser based photoacoustic setup for breath analysis. Scanning the range between 8260 and 8270 nm with a spectral resolution of 48 pm, we are able to quantify acetone and ethanol within a typical breath matrix containing water and CO2. We photoacoustically acquired spectra within this region of mid-infra-red light and prove that those spectra do not suffer from non-spectral interferences. The purely additive behavior of a breath sample spectrum was verified by comparing it with the independently acquired single component spectra using Pearson and Spearman correlation coefficients. A previously presented simulation approach is improved and an error attribution study is presented. With a 3σ detection limit of 6.5 ppbV in terms of ethanol and 250 pptV regarding acetone, our system is among the best performing presented so far. KW - Photoacoustic spectroscopy KW - quantum cascade laser KW - spectral simulation KW - breath analysis KW - acetone Y1 - 2022 U6 - https://doi.org/10.2139/ssrn.4305376 PB - Elsevier ER -