Wide-range and high-accuracy wireless sensor with self-humidity compensation for real-time ammonia monitoring.

Real-time and accurate biomarker detection is highly desired in point-of-care diagnosis, food freshness monitoring, and hazardous leakage warning. However, achieving such an objective with existing technologies is still challenging. Herein, we demonstrate a wireless inductor-capacitor (LC) chemical sensor based on platinum-doped partially deprotonated-polypyrrole (Pt-PPy and PPy) for real-time and accurate ammonia (NH) detection. With the chemically wide-range tunability of PPy in conductivity to modulate the impedance, the LC sensor exhibits an up-to-180% improvement in return loss (S11). The Pt-PPy and PPy shows the p-type semiconductor nature with greatly-manifested adsorption-charge transfer dynamics toward NH, leading to an unprecedented NH sensing range. The S11 and frequency of the Pt-PPy and PPy-based sensor exhibit discriminative response behaviors to humidity and NH, enabling the without-external-calibration compensation and accurate NH detection. A portable system combining the proposed wireless chemical sensor and a handheld instrument is validated, which aids in rationalizing strategies for individuals toward various scenarios.