Wireless Wearable MOF-Based NH3 Gas Sensor Patch with a Zeolite Overlayer for Suppressing NO2 Interference

Recent advances in flexible metal-organic framework (MOF) films have injected momentum into the development of wearable gas sensors. However, current MOF-based wearable sensors suffer from mutual interference and often compromise in power consumption and wearing comfort, limiting their suitability for skin-interfaced applications. Here, we report a wireless, battery-free, wearable gas sensor patch based on a flexible inductance-capacitance (LC) resonator. This sensor features a bilayer flexible film composed of a 2D bimetallic Cu/Co-HHTP conjugate MOF (c-MOF) sensing layer and a Pd/SSZ-13 zeolite overlayer. Specifically, the zeolite overlayer functions as an NO2-adsorbing interface that captures incoming NO2 molecules, thereby preventing them from reacting with the underlying 2D c-MOF sensing layer. Accordingly, the wireless sensor achieves linear and interference-resistant detection of low concentrated NH3 even in the presence of NO2, while maintaining excellent mechanical flexibility, cyclic stability, and negligible baseline drift, exhibiting less than 6.2% response attenuation after repeated bending at 120°. The performance of the device is further validated through a skin-adherent, wireless, passive sensing system capable of continuous NH3 monitoring in complex environments. The proposed wireless wearable MOF-based sensor patch is highly transformative, offering benefits for various wearable applications. Device performance under high-humidity conditions is still constrained, indicating that further optimization is necessary.