Graphene oxide-silver nanowires composites for protection against modern pollution - electromagnetic waves

With the development of the electronic industry, telecommunication, transportation, energy storage devices, and wireless technologies, the need for materials that are able to block electromagnetic waves (EMWs) in low-frequency regions of the spectrum is increasing. A new type of pollution named pollution by EMWs is an inevitable component of modern life. Although materials efficient in blocking the propagation of EMWs are developed, these materials show drawbacks regarding durability and mechanical properties, as well as a high production price and processability. Thus, new eco-friendly and durable materials are needed. Herein, we produced composites based on graphene oxide and silver nanowires to create an efficient shielding barrier for low frequencies (0-15 GHz) EMWs

Measurement of EMI shielding performance of graphene oxide and electrochemically exfoliated graphene thin films

Graphene and its derivatives have become the scientific community's focus due to their remarkable electronic, mechanical, and optical properties. In this work, we prepared two graphene-based materials, graphene oxide (GO) and electrochemically exfoliated graphene (EEG), and performed morphological and structural analysis. Both materials showed good dispersibility in water. GO is composed of mainly single- and few-layer graphene sheets, while EEG is predominately multi-layer graphene. EEG showed better thermal stability under nitrogen flow compared to GO. We also performed ElectroMagnetic Interference (EMI) shielding performance measurements of these materials

Graphene Oxide-Silver Nanowires Composites for Protection Against Modern Pollution – Electromagnetic Waves

With the development of the electronic industry, telecommunication, transportation, energy storage devices, and wireless technologies, the need for materials that are able to block electromagnetic waves (EMWs) in low-frequency regions of the spectrum is increasing. A new type of pollution named pollution by EMWs is an inevitable component of modern life. Although materials efficient in blocking the propagation of EMWs are developed, these materials show drawbacks regarding durability and mechanical properties, as well as a high production price and processability. Thus, new eco-friendly and durable materials are needed. Herein, we produced composites based on graphene oxide and silver nanowires to create an efficient shielding barrier for low frequencies (0-15 GHz) EMWs.29th International Symposium on Analytical and Environmental Problems : Proceedings; November 13-14, 2023; Szeged, Hungary

Determination of Photothermal and EMI Shielding Efficiency of Graphene–Silver Nanoparticle Composites Prepared under Low-Dose Gamma Irradiation

Silver nanoparticles (Ag NPs) have been produced by low-dose (1–20 kGy) gamma irradiation of silver nitrate in the presence of graphene-based material (graphene oxide or electrochemically exfoliated graphene). The large surface area of those graphene-based materials combined with the presence of oxygen-containing functional groups on the surface provided successful nucleation and growth of Ag nanoparticles, which resulted in a uniformly covered graphene surface. The obtained Ag nanoparticles were spherical with a predominant size distribution of 10–50 nm for graphene oxide and 10–100 nm for electrochemically exfoliated graphene. The photothermal efficiency measurement showed a temperature increase upon exposure to a 532 nm laser for all samples and the highest photothermal efficiency was measured for the graphene oxide/Ag NP sample prepared at 5 kGy. Electromagnetic interference (EMI) shielding efficiency measurements showed poor shielding for the composites prepared with graphene oxide. On the other hand, all composites prepared with electrochemically exfoliated graphene showed EMI shielding to some extent, and the best performance was measured for the samples prepared at 5 and 20 kGy doses

Measurement of EMI Shielding Performance of Graphene Oxide and Electrochemically Exfoliated Graphene Thin Films

Graphene and its derivatives have become the scientific community's focus due to their remarkable electronic, mechanical, and optical properties. In this work, we prepared two graphene-based materials, graphene oxide (GO) and electrochemically exfoliated graphene (EEG), and performed morphological and structural analysis. Both materials showed good dispersibility in water. GO is composed of mainly single- and few-layer graphene sheets, while EEG is predominately multi-layer graphene. EEG showed better thermal stability under nitrogen flow compared to GO. We also performed ElectroMagnetic Interference (EMI) shielding performance measurements of these materials.29th International Symposium on Analytical and Environmental Problems : Proceedings; November 13-14, 2023; Szeged, Hungary

Key Factors in the Electromagnetic Interference Shielding by Graphene-Based Composites

The overwhelming presence of electromagnetic waves created urgent need for new, eco-friendly, affordable, durable and flexible materials able to block possible interference of incident electromagnetic waves both with electronic devices and living organisms. One of the possible solutions is graphene and its composites with other nanomaterials, and polymers. Here, we discussed the main factors that comprise the electromagnetic shielding efficiency of graphene-based nanomaterials. Additionally, current issues regarding the measurement of electromagnetic shielding of materials are explained.8th IEEE Symposium on Wireless Technology and Applications, ISWTA 2024; Kuala Lumpur, 20 July 2024 - 21 July 2024

Nano-Positioning Test platform for Free-Space Six-Port Interferometric Distance Measurements

International audienceContinuous wave (CW) millimeter-wave radars have gained the interest from industry for accurate subwavelength distance measurements. In particular, the six-port radar architecture presents advantages such as high resolution combined with low-power consumption and low-cost implementation in the millimeter-wave regime. In this effort, a new test platform based on fully automated piezo-electric nanopositioning stages that simulates moving targets in XYZ directions with centimeter range combined with nanometer resolution is described. The test platform is crucial to yield performance metrics in terms of repeatability, sensitivity and accuracy. Preliminary experimental results considering a WR15 six-port CW radar designed and realized for harsh environment operation are presented to validate the approach proposed

Calibration Six-Port Basée sur une Analyse de Fourier : Extension Record de 250% des Performances Fréquentielles

National audienceUne technique de calibrage pour les démodulateurs six-port est décrite. L’architecture du démodulateur six-port est conçue à l’aide d’une jonction six-port passive, i.e. trois coupleurs hybrides et un diviseur de puissance associés à quatre détecteurs de puissance. Une modélisation de la propagation micro-onde associée à une procédure de calibrage est considérée afin d’exprimer les quatre puissances détectées en fonction des signaux I et Q. Dans ce travail, nous investiguons les limites de la modélisation classique pour des fréquences éloignées de la fréquence de travail du circuit. Nous démontrons, à titre d’exemple, qu’une modélisation appropriée basée sur une analyse de Fourier permet de surpasser les performances fréquentielles dans la bande 500 MHz – 6 GHz, limitées par le banc de mesure uniquement

Microwave Electromagnetic Shielding with Free-Standing Composites Based on Graphene Oxide and Silver Nanowires

With the growing penetration of microwave applications in modern society, exposure to electromagnetic waves (EMWs) may become an important public health problem. In addition, the coexistence of high frequency devices and systems induce electromagnetic Interferences (EMIs) leading to electromagnetic pertubations and lifetime reduction. consequently, shielding materials capable of blocking EMWs are highly needed. In this paper, composite materials based on graphene oxides and silver nanowires were studied as potential EMW shielding materials. Composites were obtained from graphene oxide (GO) with sheet size between 150 and 2000 nm and thicknesses of flakes in range 2–5 nm. Average thickness of free-standing films were around 14.8 μm . We studied the ratio between these nanomaterials to modulate shielding efficiency in a broad microwave frequency range up to 18 GHz. The shielding efficiency of around 6.5 dB was measured for the r-GO free-standing film.MARSS 2023 : 6th International Conference on Manipulation, Automation and Robotics at Small Scales; October 9-13, Abu Dhabi, United Arab Emirates, 202