On-Site Periodontitis Diagnosis via Room-Temperature Oral Exhalation H2S Sensor Based on Yb-Doped Bi2S3 Nanoribbon

H 2 S gas in oral exhalation is a critical biomarker for early periodontitis diagnosis, yet practical on-site detection via portable sensors remains challenging. Herein, we report a room-temperature H 2 S sensor based on CAU-17-derived Yb-doped Bi 2 S 3 (Yb-Bi 2 S 3 ) nanoribbons for rapid periodontitis screening. The sensor exhibits segmented linearity ranging from 5 ppb to 5 ppm, with a 3.31 response at 100 ppb, 11 s response time, and superior selectivity. Mechanism analysis combined with density functional theory calculations demonstrates that the superior detection performance originates from Yb doping-induced lattice distortion in Bi 2 S 3 , which enhances oxygen anion formation and specific H 2 S adsorption capability. Notably, the sensor quantifies H 2 S production from cultured Porphyromonas gingivalis, corroborating the correlation between oral pathogens, H 2 S, and periodontitis. Additionally, it effectively discriminates exhaled H 2 S levels on-site between healthy individuals and periodontitis patients in clinical validation. This work provides a promising platform for sensitive biomarker detection, paving the way for advanced intelligent medical diagnostics.