Breath Isoprene Sensor Based on Quartz-Enhanced Photoacoustic Spectroscopy

Abou Naoum, Fadia; Ayache, Diba; Seoudi, Tarek; Diaz-Thomas, Daniel Andres; Baranov, Alexei; Pages, Fanny; Charensol, Julien; Rosenkrantz, Eric; Aouadi, Meryem; Bahriz, Michael; Gouzi, Fares; Vicet, Aurore

doi:10.3390/s25216732

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Open AccessArticle

Breath Isoprene Sensor Based on Quartz-Enhanced Photoacoustic Spectroscopy

by

Fadia Abou Naoum

^1,†

,

Diba Ayache

^1,†,

Tarek Seoudi

¹,

Daniel Andres Diaz-Thomas

¹

,

Alexei Baranov

¹

,

Fanny Pages

¹

,

Julien Charensol

¹,

Eric Rosenkrantz

¹,

Meryem Aouadi

²,

Michael Bahriz

¹

,

Fares Gouzi

³

and

Aurore Vicet

^1,*

¹

IES, Montpellier University, CNRS, 34090 Montpellier, France

²

CHRU, 34000 Montpellier, France

³

PhyMedExp, University of Montpellier, INSERM, CNRS, CHRU, 34095 Montpellier, France

^*

Author to whom correspondence should be addressed.

^†

These authors contributed equally to this work.

Sensors 2025, 25(21), 6732; https://doi.org/10.3390/s25216732

Submission received: 2 October 2025 / Revised: 22 October 2025 / Accepted: 29 October 2025 / Published: 3 November 2025

(This article belongs to the Special Issue Advancements in Photoacoustic Sensors for Gas Detection and Air Quality Assessment)

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Abstract

Isoprene, the most abundant endogenous hydrocarbon in human breath, is a promising biomarker for metabolic and cardiovascular diseases. In this paper, we present the detection of isoprene in exhaled breath using the off-beam Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) method. The sensor employs a homemade quantum cascade laser emitting at

11.03

m

. We use numerical simulations to evaluate the impact of interfering gases (CO

_{2}

and H

_{2}

O) and optimize the laser modulation parameters. The limit of detection reached for 1 s acquisition time is close to 220 parts per billion in volume (ppbv) with a normalized noise equivalent absorption (NNEA) of

1.1 \times 10^{- 8} {cm}^{- 1} \cdot W \cdot {Hz}^{- 1 / 2}

. Breath measurements conducted on healthy volunteers reveal a significant increase in isoprene concentration from resting levels (~250–350 ppbv) to elevated levels (~450–650 ppbv) after moderate physical exercise.

Keywords: QEPAS; Photoacoustics; isoprene; breath analysis

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MDPI and ACS Style

Abou Naoum, F.; Ayache, D.; Seoudi, T.; Diaz-Thomas, D.A.; Baranov, A.; Pages, F.; Charensol, J.; Rosenkrantz, E.; Aouadi, M.; Bahriz, M.; et al. Breath Isoprene Sensor Based on Quartz-Enhanced Photoacoustic Spectroscopy. Sensors 2025, 25, 6732. https://doi.org/10.3390/s25216732

AMA Style

Abou Naoum F, Ayache D, Seoudi T, Diaz-Thomas DA, Baranov A, Pages F, Charensol J, Rosenkrantz E, Aouadi M, Bahriz M, et al. Breath Isoprene Sensor Based on Quartz-Enhanced Photoacoustic Spectroscopy. Sensors. 2025; 25(21):6732. https://doi.org/10.3390/s25216732

Chicago/Turabian Style

Abou Naoum, Fadia, Diba Ayache, Tarek Seoudi, Daniel Andres Diaz-Thomas, Alexei Baranov, Fanny Pages, Julien Charensol, Eric Rosenkrantz, Meryem Aouadi, Michael Bahriz, and et al. 2025. "Breath Isoprene Sensor Based on Quartz-Enhanced Photoacoustic Spectroscopy" Sensors 25, no. 21: 6732. https://doi.org/10.3390/s25216732

APA Style

Abou Naoum, F., Ayache, D., Seoudi, T., Diaz-Thomas, D. A., Baranov, A., Pages, F., Charensol, J., Rosenkrantz, E., Aouadi, M., Bahriz, M., Gouzi, F., & Vicet, A. (2025). Breath Isoprene Sensor Based on Quartz-Enhanced Photoacoustic Spectroscopy. Sensors, 25(21), 6732. https://doi.org/10.3390/s25216732

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Breath Isoprene Sensor Based on Quartz-Enhanced Photoacoustic Spectroscopy

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