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

Lv, Wen; Yang, Jianhua; Xu, Qingda; Mehrez, Jaafar Abdul-Aziz; Shi, Jia; Quan, Wenjing; Luo, Hanyu; Zeng, Min et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

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<sup>+</sup> and PPy<sup>0</sup>) for real-time and accurate ammonia (NH<sub>3</sub>) 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<sup>+</sup> and PPy<sup>0</sup> shows the p-type semiconductor nature with greatly-manifested adsorption-charge transfer dynamics toward NH<sub>3</sub>, leading to an unprecedented NH<sub>3</sub> sensing range. The S11 and frequency of the Pt-PPy<sup>+</sup> and PPy<sup>0</sup>-based sensor exhibit discriminative response behaviors to humidity and NH<sub>3</sub>, enabling the without-external-calibration compensation and accurate NH<sub>3</sub> 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.