Fully Integrated Photoacoustic NO<sub>2</sub> Sensor for Sub-ppb Level Measurement
A fully integrated photoacoustic nitrogen dioxide (NO<sub>2</sub>) sensor is developed and demonstrated. In this sensor, an embedded photoacoustic cell was manufactured by using an up-to-date 3D printing technique. A blue laser diode was used as a light source for excitation of photoacou...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-02-01
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| Series: | Sensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1424-8220/20/5/1270 |
| Summary: | A fully integrated photoacoustic nitrogen dioxide (NO<sub>2</sub>) sensor is developed and demonstrated. In this sensor, an embedded photoacoustic cell was manufactured by using an up-to-date 3D printing technique. A blue laser diode was used as a light source for excitation of photoacoustic wave in the photoacoustic cell. The photoacoustic wave is detected by a sensitive microelectromechanical system (MEMS) microphone. Homemade circuits are integrated into the sensor for laser diode driving and signal processing. The sensor was calibrated by using a chemiluminescence NO−NO<sub>2</sub>−NO<sub>X</sub> gas analyzer. And the performance of this sensor was evaluated. The linear relationship between photoacoustic signals and NO<sub>2</sub> concentrations was verified in a range of below 202 ppb. The limit of detection was determined to 0.86 ppb with an integration time of 1 s. The corresponding normalized noise equivalent absorption was 2.0 × 10<sup>−8</sup> cm<sup>−1</sup>∙W∙Hz<sup>−1/2</sup>. The stability and the optimal integration time were evaluated with an Allan deviation analysis, from which a detection limit of 0.25 ppb at the optimal integration time of 240 s was obtained. The sensor was used to measure outdoor air and the results agree with that obtained from the NO−NO<sub>2</sub>−NO<sub>X</sub> gas analyzer. The low-cost and portable photoacoustic NO<sub>2</sub> sensor has a potential application for atmospheric NO<sub>2</sub> monitoring. |
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| ISSN: | 1424-8220 |