PEDOT:PSS-Coated Magnetoelastic Sensors for Highly Sensitive Wireless Humidity Sensing

Wenderson R. F. Silva; Robson C. O. Guedes; Gilberto Rodrigues-Junior; Eduarda P. M. Campos; Angelo Malachias; Joaquim B. S. Mendes

arXiv · 2607.27399

PEDOT:PSS-Coated Magnetoelastic Sensors for Highly Sensitive Wireless Humidity Sensing

Wenderson R. F. Silva·Robson C. O. Guedes·Gilberto Rodrigues-Junior·Eduarda P. M. Campos·Angelo Malachias·Joaquim B. S. Mendes

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Abstract

Magnetoelastic (ME) resonators provide an attractive platform for passive and wireless sensing, particularly for monitoring relative humidity (RH) in sealed or hard-to-access environments. In this work, we introduce ME humidity sensors functionalized with poly(3,4-ethylenedioxythiophene) sulfonate (PEDOT), marking the first application of this conductive polymer in ME-based humidity sensing. PEDOT films were deposited onto Metglas resonators via a simple drop-casting process, producing uniform and mechanically stable coatings. Comprehensive structural and morphological characterization by SEM, EDX, Raman spectroscopy, AFM/KPFM, and XRD confirmed the structural integrity of the polymer and revealed humidity-induced swelling of the PSS-rich domains, accompanied by enhanced polymer-chain mobility and an increase in the lamellar spacing from 23.5 \r{A} to 24.2 \r{A} at 95% RH. These structural changes directly affected the dynamic response of the resonators, leading to a systematic resonance-frequency downshift driven by the combined effects of water adsorption, mass loading, and viscoelastic damping. The optimized device achieved a sensitivity of 155 Hz/% RH in the 20 - 70% RH range, outperforming previously reported ME humidity sensors, while exhibiting a resolution better than 0.1% RH together with excellent response and recovery times. These results establish PEDOT as a highly effective functional coating for magnetoelastic humidity sensors and demonstrate a simple, low-cost, wireless sensing platform with high sensitivity and strong potential for practical environmental and industrial monitoring applications.

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Wenderson R. F. Silva, Robson C. O. Guedes, Gilberto Rodrigues-Junior, Eduarda P. M. Campos, Angelo Malachias, Joaquim B. S. Mendes. 2026-07-29. PEDOT:PSS-Coated Magnetoelastic Sensors for Highly Sensitive Wireless Humidity Sensing. https://arxiv.org/abs/2607.27399

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