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

Area of Science:

• Materials Science
• Chemical Engineering
• Sensor Technology

Background:

• Flexible metal-organic framework (MOF) films are advancing wearable gas sensors.
• Current MOF sensors face challenges with interference, power consumption, and comfort for skin applications.

Purpose of the Study:

• To develop a wireless, battery-free wearable gas sensor patch for skin-interfaced applications.
• To overcome mutual interference issues in existing MOF-based sensors.

Main Methods:

• Fabrication of a bilayer flexible film using a 2D bimetallic Cu/Co-HHTP conjugate MOF (c-MOF) sensing layer and a Pd/SSZ-13 zeolite overlayer.
• Utilizing an inductance-capacitance (LC) resonator for wireless sensing.
• Implementing a zeolite overlayer to selectively adsorb NO2, preventing interference with NH3 detection.

Main Results:

• The wireless sensor patch demonstrated linear and interference-resistant detection of ammonia (NH3) in the presence of nitrogen dioxide (NO2).
• The device maintained excellent mechanical flexibility, cyclic stability, and negligible baseline drift, with <6.2% response attenuation after repeated bending.
• A skin-adherent, wireless, passive sensing system was validated for continuous NH3 monitoring in complex environments.

Conclusions:

• The proposed wireless wearable MOF-based sensor patch offers a transformative solution for wearable applications, addressing limitations of current technologies.
• Further optimization is needed to improve device performance under high-humidity conditions.