Flexible Room‐Temperature Ammonia Sensor Using Multi‐Heterojunction MoO₃/CuO/Cu₂O Nanoclusters for Noninvasive Kidney Disease Diagnosis

In this study, a flexible room‐temperature ammonia (NH₃) sensor is developed based on MoO₃/CuO/Cu₂O hybrid nanoclusters (HNCs), specifically designed for the noninvasive diagnosis of nephropathy. The MoO₃/CuO/Cu₂O HNCs achieve an ultralow detection limit of 0.73 ppm, with high sensitivity (0.163 ppm⁻¹) and rapid response and recovery times (16.4 and 90.6 s). The integration of MoO₃ (n‐type) with CuO and Cu₂O (p‐type) forms multi‐heterojunctions, enhancing gas‐sensing performance through efficient charge separation and improved NH₃ adsorption. Additionally, the sensor demonstrates excellent mechanical flexibility and long‐term stability under dynamic deformation. To address humidity interference in exhaled breath analysis, the sensor with a hydrophobic polytetrafluoroethylene layer is coated via radio frequency sputtering, ensuring effective NH₃ detection and differentiation between healthy individuals and kidney disease patients. In this work, the potential of multi‐heterojunction nanostructures in developing high‐performance, flexible gas sensors for practical health‐monitoring applications is highlighted.