Resonant Photoacoustic Spectroscopy of NO<sub>2</sub> with a UV-LED Based Sensor
Nitrogen dioxide (NO<sub><inline-formula>2</inline-formula></sub>) 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...
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doaj-510fb4fbffa14a19a11664cf1a2193d52020-11-25T01:51:37ZengMDPI AGSensors1424-82202019-02-0119372410.3390/s19030724s19030724Resonant Photoacoustic Spectroscopy of NO<sub>2</sub> with a UV-LED Based SensorJohannes Kapp0Christian Weber1Katrin Schmitt2Hans-Fridtjof Pernau3Jürgen Wöllenstein4Department of Microsystems Engineering—IMTEK, University of Freiburg, 79110 Freiburg, GermanyDepartment of Microsystems Engineering—IMTEK, University of Freiburg, 79110 Freiburg, GermanyDepartment of Microsystems Engineering—IMTEK, University of Freiburg, 79110 Freiburg, GermanyFraunhofer Institute for Physical Measurement Techniques IPM, 79110 Freiburg, GermanyDepartment of Microsystems Engineering—IMTEK, University of Freiburg, 79110 Freiburg, GermanyNitrogen dioxide (NO<sub><inline-formula>2</inline-formula></sub>) 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 NO<inline-formula><sub>2</sub> </inline-formula> 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<inline-formula></inline-formula> <em>σ</em>) for a cell made of aluminum.https://www.mdpi.com/1424-8220/19/3/724resonant photoacoustic spectroscopyLEDnitrogen dioxide (NO<sub>2</sub>) detectionT-cell |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Johannes Kapp Christian Weber Katrin Schmitt Hans-Fridtjof Pernau Jürgen Wöllenstein |
spellingShingle |
Johannes Kapp Christian Weber Katrin Schmitt Hans-Fridtjof Pernau Jürgen Wöllenstein Resonant Photoacoustic Spectroscopy of NO<sub>2</sub> with a UV-LED Based Sensor Sensors resonant photoacoustic spectroscopy LED nitrogen dioxide (NO<sub>2</sub>) detection T-cell |
author_facet |
Johannes Kapp Christian Weber Katrin Schmitt Hans-Fridtjof Pernau Jürgen Wöllenstein |
author_sort |
Johannes Kapp |
title |
Resonant Photoacoustic Spectroscopy of NO<sub>2</sub> with a UV-LED Based Sensor |
title_short |
Resonant Photoacoustic Spectroscopy of NO<sub>2</sub> with a UV-LED Based Sensor |
title_full |
Resonant Photoacoustic Spectroscopy of NO<sub>2</sub> with a UV-LED Based Sensor |
title_fullStr |
Resonant Photoacoustic Spectroscopy of NO<sub>2</sub> with a UV-LED Based Sensor |
title_full_unstemmed |
Resonant Photoacoustic Spectroscopy of NO<sub>2</sub> with a UV-LED Based Sensor |
title_sort |
resonant photoacoustic spectroscopy of no<sub>2</sub> with a uv-led based sensor |
publisher |
MDPI AG |
series |
Sensors |
issn |
1424-8220 |
publishDate |
2019-02-01 |
description |
Nitrogen dioxide (NO<sub><inline-formula>2</inline-formula></sub>) 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 NO<inline-formula><sub>2</sub> </inline-formula> 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<inline-formula></inline-formula> <em>σ</em>) for a cell made of aluminum. |
topic |
resonant photoacoustic spectroscopy LED nitrogen dioxide (NO<sub>2</sub>) detection T-cell |
url |
https://www.mdpi.com/1424-8220/19/3/724 |
work_keys_str_mv |
AT johanneskapp resonantphotoacousticspectroscopyofnosub2subwithauvledbasedsensor AT christianweber resonantphotoacousticspectroscopyofnosub2subwithauvledbasedsensor AT katrinschmitt resonantphotoacousticspectroscopyofnosub2subwithauvledbasedsensor AT hansfridtjofpernau resonantphotoacousticspectroscopyofnosub2subwithauvledbasedsensor AT jurgenwollenstein resonantphotoacousticspectroscopyofnosub2subwithauvledbasedsensor |
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1724997346867019776 |