Multiwavelength Photoacoustic Breath Analysis Sensor for the Diagnosis of Lung Diseases: COPD and Asthma

Breath analysis is emerging as a universal diagnostic method for clinical applications. The possibility of breath analysis is being explored vigorously using different analytical techniques. We have designed and assembled a multiwavelength UV photoacoustic spectroscopy (PAS) sensor for the said application. To optimize laser wavelength for sample excitation, photoacoustic signals from disease and normal conditions are recorded with different laser excitations (213, 266, 355, and 532 nm) on exhaled breath samples. Principal component analysis (PCA) of the PA signals has shown that 213, 266, and 355 nm laser excitations are suitable for breath analysis, with reliable descriptive statistics obtained for 266 nm laser. The study has, therefore, been extended for breath samples collected from asthma, chronic obstructive pulmonary disease (COPD), and normal subjects, using 266 nm laser excitation. PCA of the PA data shows good classification among asthma, COPD, and normal subjects. Match/No-match study performed with asthma, COPD, and normal calibration set has demonstrated the potential of using this method for diagnostic application. Sensitivity and specificity are observed as 88 and 89%, respectively. The area under the curve of the ROC curve is found to be 0.948, which justifies the diagnostic capability of the device for lung diseases. The same samples were studied using a commercial E-Nose, and the measurement outcome strongly supports the PAS results.

Automated summary

Breath analysis is an emerging universal diagnostic method for clinical applications and is being explored using different analytical techniques. A multiwavelength UV photoacoustic spectroscopy (PAS) sensor was designed for this purpose, and the optimal laser wavelengths for sample excitation were determined through recording photoacoustic signals from disease and normal conditions. The study showed that laser excitations at 213, 266, and 355 nm are suitable for breath analysis, with 266 nm laser providing reliable descriptive statistics. Further analysis of breath samples from asthma, COPD, and normal subjects using the 266 nm laser showed good classification among the groups. The study demonstrated the potential of the PAS method for diagnostic applications, with a sensitivity and specificity of 88% and 89%, respectively, and a diagnostic capability for lung diseases validated by the area under the ROC curve of 0.948. The results obtained from a commercial E-Nose also supported the PAS findings.