A SnO 2 Membrane Gas Sensor for Noninvasive Monitoring of Breath Ammonia in Hemodialysis Patients

Breath ammonia is recognized as a potential non-invasive biomarker for renal function assessment. In this study, we applied our previously developed Tin oxide (SnO2) gas sensing technology—to a new clinical application: real-time monitoring of exhaled ammonia in hemodialysis (HD) patients. The SnO2membrane gas sensor exhibited high sensitivity, low detection limit, and excellent selectivity toward ammonia due to the synergistic effects of SnO2membrane. A total of 88 HD patients were recruited, and breath samples were collected immediately before and after dialysis. Results showed a significant decrease in breath ammonia concentration post-dialysis (56.02 ± 65.72 ppm to 33.13 ± 39.57 ppm,p= 0.0021). No significant correlations were found between ammonia changes and conventional dialysis indicators (Kt/V, URR, nPCR), likely due to sampling time variability and calibration differences. This work demonstrates the potential medical application of a SnO₂-based gas sensing platform, providing a rapid and non-invasive approach that may be relevant to bedside dialysis monitoring.