Johannes Kapp
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Johannes Kapp has a total of 6 co-authors. Here are the top co-authors by number of shared publications:
- Hans-Fridtjof Pernau
Fraunhofer Institute for Physical Measurement Techniques IPM, 79110 Freiburg, Germany
2 shared publications - Katrin Schmitt
Department of Microsystems Engineering—IMTEK, University of Freiburg, 79110 Freiburg, Germany
2 shared publications - Christian Weber
Fraunhofer Institute for Physical Measurement Techniques IPM, 79110 Freiburg, Germany
1 shared publication - Christian Weber
Department of Microsystems Engineering—IMTEK, University of Freiburg, 79110 Freiburg, Germany
1 shared publication - Jürgen Wöllenstein
Laboratory for Gas Sensors, Department of Microsystems Engineering-IMTEK, University of Freiburg, Georges-Köhler-Allee 102, 79110 Freiburg, Germany
1 shared publication - Jürgen Wöllenstein
Fraunhofer Institute for Physical Measurement Techniques IPM, 79110 Freiburg, Germany
1 shared publication
Latest Publications
- Open Access
Resonant Photoacoustic Spectroscopy of NO2 with a UV-LED Based Sensor
Nitrogen dioxide (NO2) is a poisonous trace gas that requires monitoring in urban areas. Accurate measurement in sub-ppm concentrations represents a wide application field for suitable economical sensors. We present a novel approach to measure NO2 with a photoacoustic sensor using a T-shaped resonance cell. An inexpensive UV-LED with a peak wavelength of 405 nm as radiation source as well as a commercial MEMS microphone for acoustic detection were used. In this work, a cell has been developed that enables a “non-contact” feedthrough of the divergent LED beam. Thus, unwanted background noise due to absorption on the inside walls is minimized. As part of the development, an acoustic simulation has been carried out to find the resonance frequencies and to visualize the resulting standing wave patterns in various geometries. The pressure amplitude was calculated for different shapes and sizes. A model iteratively optimized in this way forms the basis of a construction that was built for gas measurement by rapid prototyping methods. The real resonance frequencies were compared to the ones found in simulation. The limit of detection was determined in a nitrogen dioxide measurement to be 200 ppb (6 σ) for a cell made of aluminum.Open AccessResonant Photoacoustic Spectroscopy of NO2 with a UV-LED Based Sensor
Nitrogen dioxide (NO2) is a poisonous trace gas that requires monitoring in urban areas. Accurate measurement in sub-ppm concentrations represents a wide application field for suitable economical sensors. We present a novel approach to measure NO2 with a photoacoustic sensor using a T-shaped resonance cell. An inexpensive UV-LED with a peak wavelength of 405 nm as radiation source as well as a commercial MEMS microphone for acoustic detection were used. In this work, a cell has been developed that enables a “non-contact” feedthrough of the divergent LED beam. Thus, unwanted background noise due to absorption on the inside walls is minimized. As part of the development, an acoustic simulation has been carried out to find the resonance frequencies and to visualize the resulting standing wave patterns in various geometries. The pressure amplitude was calculated for different shapes and sizes. A model iteratively optimized in this way forms the basis of a construction that was built for gas measurement by rapid prototyping methods. The real resonance frequencies were compared to the ones found in simulation. The limit of detection was determined in a nitrogen dioxide measurement to be 200 ppb (6 σ) for a cell made of aluminum. - Open Access
- 14 November 2018
- Published by MDPI AG in Proceedings
- Vol. 2 (13) , 1036
Resonant Photoacoustic Detection of NO2 with an LED Based Sensor
In times of steadily increasing air pollution especially in urban areas, the monitoring of nitrogen dioxide (NO2) has gained in importance and with it the search for compact, low-cost sensors. We present a novel approach to measure NO2 in sub-ppm concentrations with a photoacoustic sensor utilizing a T-shaped resonance cell. An inexpensive single LED with a peak wavelength of 410 nm was used as radiation source and the acoustic detection was done with a commercial MEMS microphone. For optimal coupling of the divergent LED light into the cell, the T-shaped resonator was developed and fabricated with rapid prototyping methods. The resonator shows a acoustic Q-factor >10 while having nearly no zero gas signal.
- 14 November 2018
- Published by MDPI AG in Proceedings
- Vol. 2 (13) , 1036
Open AccessResonant Photoacoustic Detection of NO2 with an LED Based Sensor
In times of steadily increasing air pollution especially in urban areas, the monitoring of nitrogen dioxide (NO2) has gained in importance and with it the search for compact, low-cost sensors. We present a novel approach to measure NO2 in sub-ppm concentrations with a photoacoustic sensor utilizing a T-shaped resonance cell. An inexpensive single LED with a peak wavelength of 410 nm was used as radiation source and the acoustic detection was done with a commercial MEMS microphone. For optimal coupling of the divergent LED light into the cell, the T-shaped resonator was developed and fabricated with rapid prototyping methods. The resonator shows a acoustic Q-factor >10 while having nearly no zero gas signal.