Experimental Investigation on Water Adsorption Using Laser Photoacoustic Spectroscopy and Numerical Simulations

Ammonia measurement in human breath of subjects with Helicobacter pylori using photoacoustic spectroscopy

Helicobacter pylori (H. pylori) is a type of bacteria that infects the stomach. The detection of H. pylori is an essential part of current clinical practices because this disease can cause peptic ulcers, chronic inflammation of the stomach lining but also stomach cancer. Helicobacter pylori has a naturally occurring enzyme that hydrolyzes urea into ammonium carbonate called urease. Many methods exist for the detection of H. pylori infection, but an innovative approach is to detect the ammonia in the breath (ABT, Ammonia Breath Test). In this research study, using photoacoustic spectroscopy method, the ammonia concentration in the breathing zone of people with H. pylori were measured and were compared with ammonia concentration from the respiration of healthy people. From the ABT determinations of this study, the ammonia was established to be increased with 498 ppb at people with H. pylori when we compare with ABT of healthy people.

Effect of Wearing Surgical Face Masks on Gas Detection from Respiration Using Photoacoustic Spectroscopy

Wearing surgical face masks is among the measures taken to mitigate coronavirus disease (COVID-19) transmission and deaths. Lately, concern was expressed about the possibility that gases from respiration could build up in the mask over time, causing medical issues related to the respiratory system. In this research study, the carbon dioxide concentration and ethylene in the breathing zone were measured before and immediately after wearing surgical face masks using the photoacoustic spectroscopy method. From the determinations of this study, the C₂H₄ was established to be increased by 1.5% after one hour of wearing the surgical face mask, while CO₂ was established to be at a higher concentration of 1.2% after one hour of wearing the surgical face mask, when the values were correlated with the baseline (control).

Enhancement of photoacoustic spectroscopy with sorption enrichment for ppt-level benzene detection

A real-time trace gas detector for benzene is demonstrated. The measurement system takes advantage of modest enrichment through short adsorption periods to reach a ppt-level detection limit with a sampling cycle of 90 s, which includes sample adsorption, desorption, and a spectroscopic measurement. Benzene is collected on Tenax TA sorbent for 30 s and then detected from the enriched samples with photoacoustic spectroscopy. High sensitivity is achieved using cantilever-enhanced photoacoustic spectroscopy and a continuous-wave quantum cascade laser emitting at 14.8 µm wavelength, which corresponds to the absorption wavelength of the strongest benzene infrared band. We reach a detection limit of 150 ppt of benzene, over one sampling cycle. Interference from humidity and other common petrochemicals is evaluated.