Wearable Inorganic Oxide Chemiresistor Based on Flexible Al₂O₃-Stabilized ZrO₂ Ceramic Sponge Substrate for NO₂ Sensing

Wearable gas sensors, possessing the advantages of high sensitivity, excellent flexibility, high permeability, low weight, and workability at ambient conditions, hold great promise for real-time health monitoring and early warnings of poisonous gases. However, obtaining high-performance wearable gas sensors utilizing the current well-developed inorganic semiconductor oxide sensing materials is still very limited due to their fragile and rigid nature. Herein, a newly designed wearable gas sensor based on an all-inorganic ASZ (Al₂O₃-stabilized ZrO₂)/ZnO/SnO₂ nanofibers is introduced for the first time. The flexible ASZ ceramic sponge substrate (with a Young's modulus of 4.15 MPa) and ultrathin ZnO/SnO₂ sensing layer endow the wearable gas sensor with promising properties such as super flexibility (with a bending radius of 5 mm), high gas permeability, and low weight. Furthermore, driven by UV light irradiation, this all-inorganic wearable sensor also demonstrates a stable NO₂ sensing response under different bending states at room temperature, which enables the gas sensor to be more compatible with wearable sensing applications. This work offers a general method to achieve a high-performance wearable gas sensor based on inorganic materials and provides new insights into their potential in wearable gas-sensing applications.