arXiv subjects

Wenderson R. F. Silva

Publications and source records attributed to Wenderson R. F. Silva.

4 recordsLinked to original sources

arXiv2026

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

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 Å to 24.2 Å 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.

cond-mat.mtrl-sci↗

arXiv2025

Graphene-based magnetoelastic biosensor for COVID-19 serodiagnosis

This work presents an innovative magnetoelastic (ME) biosensor using graphene functionalized with the SARS-CoV-2 N protein for antibody detection via magnetoelastic resonance. Graphene was chosen for its biocompatibility and high surface area, enabling efficient antigen adsorption, validated by techniques such as energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM), and micro-Raman spectroscopy. Changes in Raman bands (a $\sim 10~\mathrm{cm}^{-1}$ shift in the 2D band and an increase in the $I_D/I_G$ ratio from 0.03 to 0.60) confirmed non-covalent interactions and enhanced surface coverage with ~100 $μ$g of N protein. Tests using human plasma (10 RT-PCR-positive and 10 negative samples) demonstrated a clear distinction between groups using graphene sensors functionalized with ~100 $μ$g of N protein. Enzyme-linked immunosorbent assay (ELISA) validation corroborated the results. Optimization of protein concentration and biofunctionalization time highlighted the importance of homogeneous surface coverage for reproducibility of the graphene-based ME biosensor. The platform combines graphene's advantages with the wireless, real-time detection capabilities of ME sensors, offering low cost, high sensitivity, and potential for automation, with applications in point-of-care diagnostics.

physics.bio-ph↗

arXiv2024

Development of an integrated device based on the gain/phase detector and Arduino platform for measuring magnetoelastic resonance

This study presents the development of an integrated device for measuring magnetoelastic resonance, utilizing a gain/phase detector and the Arduino platform. The device stands out for its simplicity, low cost, and efficiency. It employs the Arduino's ATmega328P microcontroller, coupled with the AD8302, and an intuitive graphical interface developed in Python, which facilitates the measurement of magnetoelastic signals in sensors. The device's validation is carried out through measurements of mass deposits on magnetoelastic sensors, confirming its accuracy and functionality. This advancement offers a practical and portable solution for detecting magnetoelastic resonances, promoting the use of these technologies in field environments and in diverse scientific applications. The integration of components into a compact, robust, and low-cost electronic circuit, along with an easy-to-operate graphical interface, significantly simplifies the complexity of the components, making the equipment complete and readily operational.

physics.ins-det↗

arXiv2024

A biosensor based on magnetoelastic waves for detection of antibodies in human plasma for COVID-19 serodiagnosis

The study proposes a new efficient wireless biosensor based on magnetoelastic waves for the detection of antibodies in human plasma, aiming at the serological diagnosis of COVID-19. The biosensor was functionalized with the N antigen - nucleocapsid phosphoprotein of the SARS-CoV-2 virus. Validation analyses, by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE), Western blotting, atomic force microscopy (AFM), scanning electron microscopy (SEM), micro-Raman spectroscopy, confirmed the selectivity and effective surface functionalization of the biosensor. The research successfully obtained, expressed and purified the recombinant antigen, while plasma samples from COVID-19 positive and negative patients were used to test the performance of the biosensor. A comparison of performance with the ELISA method revealed equivalent diagnostic power. These results indicate the robustness of the biosensor in reliably differentiating between positive and negative samples, highlighting its potential as an efficient and low-cost tool for the serological diagnosis of COVID-19. In addition to being fast to execute and having the potential for automation in large-scale diagnostic studies, the biosensor fills a significant gap in existing SARS-CoV-2 detection approaches.

physics.bio-ph↗