A high-performance room-temperature biomass carbon-based nitric oxide (NO) gas sensor used to diagnose asthma and monitor its severity clinically

Fractional exhaled nitric oxide (FeNO) has been identified as a biomarker for asthma that can aid in both its diagnosis and severity monitoring. Here, a high-performance NO gas sensor based on rGO-decorated biomass carbon was fabricated. Operating at room temperature, the sensor can detect 50 ppb NO in exhaled breaths, which is a critical concentration threshold in asthma diagnosis and management. Clinically, 11 exhaled breath samples from asthma patients and 13 from healthy controls were collected. The sensor successfully discriminated between asthma patients and healthy controls directly via the response values. The severity of asthma in three inpatients was monitored using the sensor in parallel with the clinical standard tool, the peak flow meter. A high degree of consistency was observed between the severity monitoring results obtained by the two methods. Specifically, a strong positive correlation between the sensor's response values and the clinical standard diurnal PEF variation was found, with a Pearson correlation coefficient of r = 0.84 (p<0.05), further validating the sensor's reliability for monitoring asthma severity. This sensor holds significant potential for clinical application in asthma diagnosis and could replace current, complex, and limited PEF testing methods for asthma severity monitoring.