Detecting Breath Ammonia for Non-invasive Diagnostic based on Low-Cost Organic Diode with Vertical Nanojunctions

We propose a novel solid-state electrical ammonia sensor based on a vertical organic diode with high-density nanopores in the top electrode. The proposed ammonia sensor has a detection limit of 20 ppb, a real-time response, sufficient selectivity, simple structure, high reproducibility, and a low production cost. In addition, we used the proposed sensor to detect the nasal breath of rats directly. After controlling the relative humidity and filtering out the CO2, we successfully obtained repeated real-time, reliable responses. This is the first demonstration of a solid-state sensor having reliable responses to the breath ammonia of an animal. The sensing response between normal and acute groups is significantly different (p < 0.05). These results demonstrated that the proposed ammonia sensor can detect liver that undergoes moderate hepatopathy.