Double-walled carbon nanotube-based polymer composites for electromagnetic protection.

In this paper, we present a microwave absorber based on carbon nanotubes (CNT) dispersed inside a BenzoCycloButenw (BCB) polymer. The high aspect ratio and remarkable conductive characteristics of CNT give rise to good absorbing properties for electromagnetic protecting in microelectronic devices with very low concentration. In this article, nanocomposites are prepared using a solution-mixing method and are then evaluated and modeled by means of coplanar test structures. First, CNT concentrations are quantified by image processing. The nanocomposites implemented with coplanar test waveguides are then characterized using a vector network analyzer from 40 MHz to 20 GHz. An algorithm is developed to calculate the propagation constant "γ" constant "α", and relative effective complex permittivity (εreff = εreff' - jεreff'') for each CNT concentration. The extracted effective parameters are verified using the electromagnetic FEM-based Ansoft’s® high frequency structure simulator (HFSS). Power absorption (PA) of 7 dB at 15 GHz is obtained with only 0.37 weight percent of CNT concentration in the polymer matrix. The resulting engineerable and controllable composite provides consequently a novel degree of freedom to design and optimize innovative microwave components

Millimeter wave carbon nanotube gas sensor

This Letter reports experimental observations regarding the significant changes in the transmission modulus and phase of the propagating microwave signals up to 110 GHz in a micromachined coplanar waveguide supported on a dielectric membrane with a thickness of 1.4 m filled with a mixture of carbon nanotubes when exposed to nitrogen gas. These large shifts of amplitude and phase of microwave signals due to gas absorption represent the experimental basis on which a miniature wireless gas sensor could be implemented

Experimental determination of microwave attenuation and electrical permittivity of double-walled carbon nanotubes

The attenuation and the electrical permittivity of the double-walled carbon nanotubes (DWCNTs) were determined in the frequency range of 1–65 GHz. A micromachined coplanar waveguide transmission line supported on a Si membrane with a thickness of 1.4 µm was filled with a mixture of DWCNTs. The propagation constants were then determined from the S parameter measurements. The DWCNTs mixture behaves like a dielectric in the range of 1–65 GHz with moderate losses and an abrupt change of the effective permittivity that is very useful for gas sensor detection. ©2006 American Institute of Physic

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Les micro-nanotechnologies pour les systèmes hyperfréquences: au-delà des conventions

L'évolution de notre société est spectaculaire. Les nouvelles technologies apportent sans cesse des bouleversements dans nos vies, dont nous n'avons d'ailleurs pas toujours conscience tellement ces changements sont rapides et naturels. Qui aujourd'hui ne possède pas un téléphone portable extra miniature, possédant de multiples fonctionnalités intégrées: appareil photo, boussole, loupe...? Qui n'a pas entendu parlé des progrès phénoménaux réalisés en médecine avec, par exemple, la technique d'Imagerie par Résonance Magnétique (IRM) ou encore l'utilisation par les chirurgiens d'outils extrêmement précis, assistés par ordinateur? Parmi ce contexte très général de révolutions technologiques, ma simple contribution se situe dans le développement de microsystèmes hyperfréquences, que ce soit : pour les communications et transfert d'informations avec des modules toujours plus performants et agiles (multifonctionnalité), et plus récemment pour les domaines de la biologie et du médical avec le développement de systèmes d'analyse par ondes électromagnétiques hautes fréquences. La démarche scientifique adoptée vise à établir, grâce aux microtechnologies, de nouvelles perspectives d'exploitation des microsystèmes hyperfréquences, au-delà des technologies conventionnelles. Ceci commence par l'élaboration de circuits passifs à fort coefficient de qualité, leur intégration tridimensionnelle vers toujours plus de miniaturisation et fréquences de fonctionnement plus élevées, l'évaluation de matériaux inédits (notamment à base de nanotubes de carbone) qui apportent de nouvelles possibilités aux concepteurs HF, de concepts innovants de composants à forte reconfigurabilité, que ce soit par une approche mécanique avec les MEMS RF, ou encore avec des liquides, jusque de nouvelles applications pour les domaines de la biologie et du médical, l'environnement et même l'agro-alimentaire

Guest Editorial

International audienceThe IEEE IMWS is an initiative promoted by the IEEE MTT-S Members and Geographic Committee to complement the existing workshops of the IEEE MTT-S International Microwave Symposium (IMS). The purpose of this platform is to boost and promote IEEE MTT-S technical and educational activities, as well as IEEE MTT-S international exchanges and collaborations. The 2014 IMWS-Bio workshop was technically cosponsored by the IEEE MTT-S, the IEEE Antennas and Propagation (AP) Society, and the Institution of Engineering and Technology (IET). The conference, which was held in London, U.K., was the perfect setting for such multidisciplinary event focusing on innovation cutting-edge research. The workshop hosted 8 world-renowned keynote speakers, 22 excellent invited talks, and a special distinguished banquet evening talk. The IMWS-Bio 2014 received a total submission of 120 papers, including invited papers and regular papers from 24 countries with 120 registrants at the event itself. After performing rigorous and thorough technical reviews, all of the invited papers and 70 regular papers were accepted for oral and poster presentations divided into 10 oral sessions and two main poster sessions. The conference also included a quick-fire presentation session for Best Student Paper contest finalists (8 were selected) and the contest was judged by a panel of international experts in the fields. The IEEE BioWireleSS has been since 2011 an event specifically dedicated to wireless developments in the exciting biomedical fields. Its multidisciplinary aspects are cosponsored by several societies, i.e

The IEEE International Microwave Biomedical Conference 2020

International audienc

Evaluation of the impact of RF electromagnetic waves on cells with near-field exposure instrumentations

Presentation during the Workshop WSC « Health aspects of mm-wave radiation in 5G and beyond »International audienceRadioFrequency electromagnetic (EM) waves constitute nowadays common and ubiquitous elements of our surrounding and living environment. They are not only employed in military applications, but also increasingly used in our daily life for various exploitations: wireless communications, radars for automotive, home automation and now the tremendous market of connected objects. Their impact on the human health remains however a large question mark with controversial investigations results performed at different levels, microscopic and macroscopic ones, as well as at the population level with epidemiologic studies. Within this context, this presentation aims at highlighting the reasons for such a controversy, recalling different interaction mechanisms, which may occur between EM waves and the living, and also presenting near-field RF exposure systems developed at LAAS-CNRS in collaboration with different partners

Evaluation of the impact of RF electromagnetic waves on cells with near-field exposure instrumentations

Presentation during the Workshop WSC « Health aspects of mm-wave radiation in 5G and beyond »International audienceRadioFrequency electromagnetic (EM) waves constitute nowadays common and ubiquitous elements of our surrounding and living environment. They are not only employed in military applications, but also increasingly used in our daily life for various exploitations: wireless communications, radars for automotive, home automation and now the tremendous market of connected objects. Their impact on the human health remains however a large question mark with controversial investigations results performed at different levels, microscopic and macroscopic ones, as well as at the population level with epidemiologic studies. Within this context, this presentation aims at highlighting the reasons for such a controversy, recalling different interaction mechanisms, which may occur between EM waves and the living, and also presenting near-field RF exposure systems developed at LAAS-CNRS in collaboration with different partners