Room-temperature ammonia sensing enabled by a novel green-exfoliated disordered graphene/albumen composite for wearable human monitoring

The advancement of wearable and human-centered electronics drives increasing demand for high-speed, reliable chemical sensors capable of detecting physiologically relevant signals. Among various target analytes, ammonia (NH 3 ) is of particular importance due to its relevance in environmental exposure assessment and noninvasive health monitoring. However existing wearable NH 3 sensors are often limited by slow response dynamics, rigid material systems, and poor tolerance to humidity and temperature variations. Herein, these challenges are addressed by integrating a disordered graphene–protein composite with a micro-gap electrode architecture. Exfoliated disordered graphene ( EG ), synthesized via a scalable solvent-assisted exfoliation process, is combined with chicken egg-derived albumen to form a conductive and biocompatible sensing layer interfaced with ∼13 µm micro-gap electrodes. Owing to the synergistic dual-sensing mechanism arising from EG and protein functional groups, the sensor exhibits fast response and recovery times of 0.7 s and 1.1 s, respectively, toward 5 ppm NH 3 at room temperature. The test gas was injected in the test chamber close to the sensor surface. Systematic investigations revealed that the NH 3 response is influenced by environmental conditions, with (absolute) resistance magnitude decreasing under elevated humidity and temperature due to enhanced adsorption and charge-transfer processes. Leveraging these attributes, real-time NH 3 detection is demonstrated under physiological temperature conditions and for urine-derived ammonia. This work establishes a sustainable and high-performance sensing strategy for next-generation wearable monitoring technologies.