Wireless Gas Sensors Enabled by Conjoined Conduction-Polarization Mechanisms for Room Temperature ppb-Level...

Volatile organic compound (VOC) detection is of great significance in environmental diagnosis and food science. Conventional metal oxide-based VOC sensors rely on a 1-fold, energy-activated sensing mechanism, rendering a grand challenge of highly sensitive VOC sensing at room temperature (RT). Herein, a phthalic anhydride (PA)-based inductor-capacitor (LC) wireless sensor for real-time triethylamine (TEA) sensing is reported. The TEA-stimulated PA film exhibits conjoined conduction-polarization mechanisms, contributing to conductometric and dielectrometric variations with rapid and specific reaction kinetics. A wireless LC resonator utilizing a single electrical parameter (S11) to collect the conductometric and dielectrometric transducing signals is designed, enabling a lower detection limit (300 ppb) and a response/recovery time of 29 s/261 s at RT. As a prototype, a portable system combining a wireless LC sensor and hand-held instrument is demonstrated in food freshness identification. This conjoined conduction-polarization mechanisms shed light on the rational design of high-efficiency chemical sensors at both the material and device levels.