Differential, LED-excited, resonant NO2 photoacoustic system

Bernhardt, René; Santiago, Guillermo; Slezak, V.; Peuriot, A.; González, Martín

doi:10.1016/j.snb.2010.09.007

Cited by 23 publications

(18 citation statements)

References 5 publications

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“…The gas detection scheme is intimately related to the original URAS design (Lehrer and Luft, 1942), but considerably simplifies the setup. While in the past highly sensitive and sophisticated, photoacoustic-based approaches have been demonstrated (Bernhardt et al, 2010;Elia et al, 2009;Sigrist, 2007, 2008;Wu et al, 2017), only recently has the potential for simple yet reliable devices started to gain attention. An early setup to miniaturize the URAS was demonstrated about a decade ago using pressure sensors to gauge the light intensity (Schjølberg-Henriksen et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

“…An early setup to miniaturize the URAS was demonstrated about a decade ago using pressure sensors to gauge the light intensity (Schjølberg-Henriksen et al, 2008). Since then, both thermal emitters as well as light-emitting diodes (LEDs) have been used in combination with gas-based detectors to build gas sensors (Bierer et al, 2018;Knobelspies et al, 2016;Köhring et al, 2015;Kuusela et al, 2009;Scholz et al, 2017;Scholz and Palzer, 2016;Wittstock et al, 2017;Uotila, 2007;Lindley et al, 2007;Chen et al, 2005;Karioja et al, 2010) for various applications. Additionally, we present a simulation comparing the sensitivity of standard NDIR and photoacoustic-based NDIR to highlight the potential for miniaturization when using a gas-based detector.…”

Section: Introductionmentioning

confidence: 99%

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Gas sensors for climate research

Scholz

Pérez

Bierer

et al. 2018

J. Sens. Sens. Syst.

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Abstract. The availability of datasets providing information on the spatial and temporal evolution of greenhouse gas concentrations is of high relevance for the development of reliable climate simulations. However, current gas detection technologies do not allow for obtaining high-quality data at intermediate spatial scales with high temporal resolution. In this regard the deployment of a wireless gas sensor network equipped with in situ gas analysers may be a suitable approach. Here we present a novel, non-dispersive infrared absorption spectroscopy (NDIR) device that can possibly act as a central building block of a sensor node to provide high-quality data of carbon dioxide (CO2) concentrations under field conditions at a high measurement rate. Employing a gas-based, photoacoustic detector we demonstrate that miniaturized, low-cost, and low-power consuming CO2 sensors may be built. The performance is equal to that of standard NDIR devices but at a much reduced optical path length. Because of the spectral properties of the photoacoustic detector, no cross-sensitivities to humidity exist.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gas sensors for climate research

Scholz

Pérez

Bierer

et al. 2018

J. Sens. Sens. Syst.

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“…Laser sources from the ultraviolet (UV) to the far infrared region (FIR) have been applied to environmental monitoring, industrial process control and noninvasive medical diagnostics [6][7][8][9][10][11]. The photoacoustic transducer commonly used for sound wave detection in PAS is a microphone [12][13][14], a fiber tip [3,6] or a quartz tuning fork [4,5,8,[15][16][17][18][19][20][21]. The principle of PAS is to detect the sound waves generated from the gas molecules upon absorption of the excitation radiation, whose frequency is resonant with the vibrational or rotational energy levels of the target gas molecule [2].…”

Section: Introductionmentioning

confidence: 99%

Compact photoacoustic module for methane detection incorporating interband cascade light emitting device

et al. 2017

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A photoacoustic module (PAM) for methane detection was developed by combining a novel 3.2 μm interband cascade light emitting device (ICLED) with a compact differential photoacoustic cell. The ICLED with a 22-stage interband cascade active core emitted a collimated power of ~700 μW. A concave Al-coat reflector was positioned adjacent to the photoacoustic cell to enhance the gas absorption length. Assembly of the ICLED and reflector with the photoacoustic cell resulted in a robust and portable PAM without any moving parts. The PAM performance was evaluated in terms of operating pressure, sensitivity and linearity. A 1σ detection limit of 3.6 ppmv was achieved with a 1-s integration time.

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“…Ambient acoustic noise and flow noise may also couple to the PA signal, thus hinder sensitive measurements. In order to obtain an efficient noise suppression and improve the signal to noise ratio (SNR), many different designs of PA cells have been proposed and tested, aiming at various aspects of signal improvement, noise reduction, and ease * Corresponding author: ml@dfm.dk of use [10][11][12][13][14][15][16]. In this paper it is demonstrated that the use of higher order acoustic modes increases the sensitivity by reducing the coupling of flow noise to the PA sensing devices and a further increase is shown by using two microphones in the same acoustic resonator (PA cell).…”

Section: Introductionmentioning

confidence: 99%

Phase-sensitive noise suppression in a photoacoustic sensor based on acoustic circular membrane modes

et al. 2015

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A photoacoustic (PA) sensor based on higher order acoustic modes is demonstrated. The PA sensor is designed to enhance the gas-detection performance and simultaneously suppress ambient noise sources (e.g. flow noise, electrical noise and external acoustic noise). Two microphones are used and positioned such that the PA signals are (π) out of phase. Ambient acoustic noise are approximately in the same phase and will be subtracted and thus improve the SNR. In addition, by placing the gas in-and outlets so that the gas flows through the node of the first higher order membrane mode the coupling of flow noise is approximately 20 dB lower compared with flow through the fundamental mode at 5 L/min. The noise reduction and thus the increase in sensitivity is demonstrated by measuring vibrational lines of methanol and methane using a broadband interband cascade laser emitting radiation at 3.38 µm. A signal-to-noise improvement of 20 (26 dB) using higher order modes are demonstrated compared with the fundamental mode. The maximum normalized noise equivalent absorption coefficient is 1.1 ×10 −6 W cm −1 Hz 1/2 for a flow of 5 L/min. It is anticipated that the noise cancelation strategy may find use in many practical industrial and environmental PA sensors, where ambient noise sources plays a crucial role for the absolute sensitive.

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Differential, LED-excited, resonant NO2 photoacoustic system

Cited by 23 publications

References 5 publications

Gas sensors for climate research

Gas sensors for climate research

Compact photoacoustic module for methane detection incorporating interband cascade light emitting device

Phase-sensitive noise suppression in a photoacoustic sensor based on acoustic circular membrane modes

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