Dual Absorption Broadband Photoacoustic Technique to Eliminate Interference in Gas Mixtures
K. Saran Kumar, Y. Esther Blesso Vidhya, Ramya Selvaraj, Satyanarayanan Seshadri, S. M. Shiva Nagendra, Nilesh J. Vasa
Abstract
This article presents a dual-wavelength band broadband photoacoustic spectroscopy (BPAS) technique ideally suited to low-energy broadband sources for industrial and environmental multigas sensing applications. The broad spectral range of the supercontinuum source is used to cover a wide range of absorption bands of various gases. The major limitation in most of the gas sensors with broadband sources is the effect of interference between gases. This article proposes a dual-wavelength technique to eliminate the impact of cross sensitivity among gases. This sensor exhibits a comprehensive concentration measurement from parts per million (ppm) to % levels. The proposed technique showed a ±1.2% error between the calculated and calibrated concentration values. We achieved a minimum detection limit (MDL) of 0.4 and 0.7 ppm for methane (CH4) with an integration time of 142 and 200 s using 2315- and 1650-nm band, respectively, 0.3 and 1.8 ppm of ammonia (NH3) with an integration time of 100 and 48 s using 2315- and 2017-nm band, respectively, and also 2.6 ppm of carbon monoxide (CO) with an integration time of 71 s using the 2315-nm band.