Non-Local Patch Regression Algorithm-Enhanced Differential Photoacoustic Methodology for Highly Sensitive Trace Gas Detection

• Published in: Chemosensors Vol. 9; no. 9; p. 268
• Main Authors: Zhang, Le, Liu, Lixian, Huan, Huiting, Yin, Xukun, Zhang, Xueshi, Mandelis, Andreas, Shao, Xiaopeng
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2021
• Subjects: Absorption spectra; Algorithms; Background noise; Broadband; Carbon dioxide; Data processing; Gas absorption; Gas analysis; gas sensors; Gases; Laboratories; Light; multi-component; Noise; Noise reduction; non-local denoising algorithm; photoacoustic spectroscopy; Radiation; Sensors; Signal processing; Signal to noise ratio; Spectrum analysis; Trace gases; Wavelet analysis; Wavelet transforms
• ISSN: 2227-9040; 2227-9040
• DOI: 10.3390/chemosensors9090268

A non-local patch regression (NLPR) denoising-enhanced differential broadband photoacoustic (PA) sensor was developed for the high-sensitive detection of multiple trace gases. Using the edge preservation index (EPI) and signal-to-noise ratio (SNR) as a dual-criterion, the fluctuation was dramatically suppressed while the spectral absorption peaks were maintained by the introduction of a NLPR algorithm. The feasibility of the broadband framework was verified by measuring the C2H2 in the background of ambient air. A normalized noise equivalent absorption (NNEA) coefficient of 6.13 × 10−11 cm−1·W·Hz−1/2 was obtained with a 30-mW globar source and a SNR improvement factor of 23. Furthermore, the simultaneous multiple-trace-gas detection capability was determined by measuring C2H2, H2O, and CO2. Following the guidance of single-component processing, the NLPR processed results showed higher EPI and SNR compared to the spectra denoised by the wavelet method and the non-local means algorithm. The experimentally determined SNRs of the C2H2, H2O, and CO2 spectra were improved by a factor of 20. The NNEA coefficient reached a value of 7.02 × 10−11 cm−1·W·Hz−1/2 for C2H2. The NLPR algorithm presented good performance in noise suppression and absorption peak fidelity, which offered a higher dynamic range and was demonstrated to be an effective approach for trace gas analysis.