Photoacoustic Approach Using a Broadband
Laser Source for Sensing Carbon Monoxide and Carbon Dioxide
Saran Kumar K 1, Esther Blesso Vidhya Y 1, Ramya Selvaraj 2, Satyanarayanan S 1,
Nilesh J Vasa 1
1 Indian Institute of Technology Madras, Chennai, 600036, India
2 National Institute of Technology, Raipur, Raipur, 492010, India
Wide Range of Gas Sensing Applications
Carbon Monoxide (CO) : Sources and Effects
Carbon monoxide is a colorless and odorless gas
Common Sources of CO:
Man made and Natural
CO Poisoning in Human
Rose, J. J., Wang, L., Xu, Q., McTiernan, C. F., Shiva, S., Tejero, J., & Gladwin, M. T. (2017). Carbon Monoxide Poisoning: Pathogenesis, Management, and Future
Directions of Therapy. American journal of respiratory and critical care medicine, 195(5), 596–606. https://doi.org/10.1164/rccm.201606-1275CI.
Carbon Dioxide (CO2) : Sources and Effects
Carbon dioxide is colorless and odorless at low concentrations
Common Sources of CO2:
Man made and Natural
CO2 Effects
Jinlo Dong, & Nazim Garud (2018) Effects of Elevated CO2 on Nutritional Quality of Vegetables: A Review, Front. Plant Sci., 195(5), 596–606
https://doi.org/10.3389/fpls.2018.00924.
Photoacoustic Effect
Steps in Generation and Detection of PA Signal
T. Yang, W. Chen, and P. Wang, “A review of all-optical photoacoustic spectroscopy as a gas sensing method,” Applied Spectroscopy Reviews, vol. 56, no. 2, pp.
143–170, 2021.
Broadband Photoacoustic Spectroscopy
Carbon monoxide
Carbon dioxide
Where,
Umin is the minimum detectable
microphone signal at SNR = 3dB and Smic
is the microphone responsivity.
Experimental Setup – Laboratory Based
Results and Discussion
Moisture absorption around the same region of CO2
 In breath gas sensing, the interference of water vapour and CO2 with other Volatile Organic
Compounds (VOC’s) can be eliminated by performing cross sensitivity studies or by employing
suitable traps.
Results and Discussion
Direct Absorption
PA Spectroscopy
 After passing through the CO2 trap a significant drop in the absorption and in the PA amplitude
is observed. A minimum detection limit of 480 ppm was achieved using DAS.
Results and Discussion
MDL achieved using a supercontinuum laser source with low optical power
Results and Discussion
Lower detection limits are achieved using a supercontinuum laser source with higher optical power
Summary
A novel approach using broadband photoacoustic spectroscopy (PAS) is proposed
and demonstrated for sensing carbon monoxide and carbon dioxide.
 Broadband PA spectroscopy with a supercontinuum laser is used for high sensitivity
measurement.
 A minimum detection limit of 6 ppm for CO and 0.645 ppm for CO2 was measured
with SNR of 3 dB.
 Interference of H2O with CO2 was eliminated using a suitable trap system or by
employing cross sensitivity studies.
This technique can be used for sensing, automobile/Industrial exhaust gas
monitoring, breath gas analysis etc.,
Acknowledgment
The authors are grateful for the PMRF (Prime Minister’s Research Fellowship) and
project titled “Development of broadband photoacoustic interferometry technique
for ammonia and acetone detection in exhaled breath matrix”
‘SP21221104EDSERB00823’ for the funding to carry out the research.
The authors thank IITM central workshop for their assistance in this research.
Thank You