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A 250 MHz to 1.1 THz sub-mm wave on-wafer characterization of InP HEMT using a multiline Thru-Reflect-Line calibration kit
No full textInternational audienceAbstract In this paper, we report an on-wafer High-Electron-Mobility transistor characterization method over a large frequency band [250 MHz–1.1 THz]. The transistor’s coplanar accesses were optimized to enable high-frequency measurement of the devices up to 1.1 THz. The characterization method implements an on-wafer multiline Thru-Reflect-Line calibration kit fabricated on indium phosphide (InP) substrate validated using comparisons between simulations and measurements of coplanar waveguide (CPW) devices. An 80-nm gate length InAlAs/InGaAs/InAs InP-HEMT was fabricated using the optimized transistor accesses then it was measured over the [250 MHz–1.1 THz] frequency band using the developed on-wafer characterization method. It is important to mention that the same transistor was measured on six different on-wafer test benches [250 MHz–110 GHz], [140–220 GHz], [220–325 GHz], [325–480 GHz], [500–750 GHz], and [750–1100 GHz]. The S-parameter measurement results show good continuity between the six measured frequency bands. Observations on the extracted gain measurements and a comparison between the measured and [250 MHz–110 GHz] extrapolated cut-off frequencies are also provided
Couche dissipative pour nanostructuration de résine HSQ par lithographie électronique sur substrat isolant
No full textInternational audienceDissipative layer is a key element in nanopatterning resist such as HSQ on insulating substrates. At IEMN we are currently investigating different strategies to avoid surface charging effect. Since a single top layer of Ge or Au leads to non-conform patterning, the first approach involves transferring a graphene monolayer prior the HSQ deposition. The second path deals with transparent conductive polymer layers. For the bottom layer, the polymer is cross-linked for stability purposes and requires a post-treatment to improve the resulting degraded conductivity. For upper layer, the polymer is mixed a surfactant that allow a good spreading on HSQ and with a polar solvent which promotes both conductivity and polymer swelling to facilitate lift-off in water prior the HSQ development. Last but not least, a sacrificial positive metallic mesh can be patterned using a positive lithography and subsequent etching by RIBE prior the negative HSQ is written. We hope those developments will pave the way to useful breakthroughs for the e-beam lithography community.La couche dissipative est un élément clé dans les résines nanostructurées telles que le HSQ sur des substrats isolants. À l'IEMN, nous étudions actuellement différentes stratégies pour éviter l'effet de charge superficielle. Étant donné qu'une seule couche supérieure de Ge ou d'Au entraîne une structuration non conforme, la première approche consiste à transférer une monocouche de graphène avant le dépôt de HSQ. La deuxième approche concerne les couches de polymères conducteurs transparents. Pour la couche inférieure, le polymère est réticulé à des fins de stabilité et nécessite un post-traitement afin d'améliorer la conductivité dégradée qui en résulte. Pour la couche supérieure, le polymère est mélangé à un tensioactif qui permet une bonne répartition sur le HSQ et à un solvant polaire qui favorise à la fois la conductivité et le gonflement du polymère afin de faciliter le décollage dans l'eau avant le développement du HSQ. Enfin, un maillage métallique positif sacrificiel peut être modelé à l'aide d'une lithographie positive, puis gravé par RIBE avant l'écriture du HSQ négatif. Nous espérons que ces développements ouvriront la voie à des avancées utiles pour la communauté de la lithographie par faisceau électronique
Co-Effect of pH Control Agent and pH Value on the Physical Properties of ZnO Thin Films Obtained by Chemical Bath Deposition for Potential Application in Dye-Sensitized Solar Cells
No full textInternational audienceThis study presents the influence of pH control agents and pH value on the physical properties of ZnO thin films obtained by chemical bath deposition. ZnO thin films were synthesized on glass substrates using precursor solutions of different pHs prepared from two bases: sodium hydroxide (NaOH) and ammonia (NH3). The effect of pH values on the morphological, structural, and optical properties of ZnO thin films was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and UV-Visible spectroscopy. XRD results showed that all the synthesized ZnO thin films are polycrystalline and crystallize in a hexagonal wurtzite structure. The crystallite size, calculated using the Debye-Scherrer formula, varied from 10.50 nm to 11.69 nm for ZnO thin films obtained with NH3 and from 20.79 nm to 27.76 nm for those obtained with NaOH. FTIR analysis confirmed the presence of functional groups. SEM images indicated that not only the base but also the pH affects the morphology of the films, giving rise to different granular shapes. Overall, the ZnO thin films obtained with NaOH looked more mesoporous compared to those obtained with NH3. Optical characterization results showed that whatever the base used, the pH of the precursor solution affected the ZnO thin film transmittance. Films synthesized with NH 3 exhibited the best transmittance (80%) at pH 8.5, while the best transmittance (81%) of films synthesized with NaOH was obtained at pH 8 in the visible region. Based on optical and morphological properties, ZnO films obtained from NH3 at pH 8.5 are found to be more suitable as photoanodes in dye-sensitized solar cells
Contact forces move a particle along an acoustically excited surface: Case of permanent contact
No full textInternational audienceIt is known that solid particles can move along vibrating surfaces due to the action of oscillating contact forces. The effect is used for sorting or transporting particles (granular mixtures or powders) in food and pharmaceutical industries. Future applications can include actuating micro-devices, dust removal, or delivery of active components to heal damaged structures etc.A practical particle manipulation system has a number of parameters related to the vibration/wave as well to material properties. Therefore, to observe a desired motion effect, a multi-parametric system optimization can be done based on a model rather that in a purely empirical way. In this paper, we consider a deformable axisymmetric particle posed on a deformable substrate, in contrast to a more traditional treatment that uses a point mass. For the axisymmetric contact system, there exist analytical solutions of a Cattaneo-Mindlin type. Here we apply an original recent generalization of the approach referred to as the Method of Memory Diagrams. It provides an automated hysteretic solution to the contact problem applicable to an arbitrary excitation in terms of normal and tangential contact displacements. An algorithmic link between contact loads and displacements allows one to numerically solve the equations of motion. At the same time, it can be demonstrated that only two essential parameters’ combinations determine the system behavior, the effective mass and normalized wave amplitude. In the functional space of these parameters, various regimes are seen.Depending on functional parameters, the particle stays in permanent contact with the substrate or experiences multiple rebounds. Here we consider the former case in which the drift can appear due to a phase mismatch between the normal and tangential forces. The Coulomb friction results in the fact that the tangential motion is more efficient during the phase of unloading than during a high compression phase. In other words, the unloading phase corresponds to advancing motion while in the loading phase the particle recedes i.e. moves in the opposite direction but covers a considerably shorter distance. At longer time scales this kind of motion looks like a directed drift that can be used for particle manipulation
Classification des mécanismes d'usure lors du formage d'aluminium à haute température par apprentissage automatique et profond
No full textInternational audienceGreen manufacturing focuses lubricant-free forming in order to reduce costs and minimise environmental impact. In the case of high-temperature forming of aluminium alloys, this approach, which results in direct contact between the part and the tools, leads to material transfer and surface defects. Although amorphous carbon coatings, such as DLC, mitigate these problems, they remain prone to mechanical wear and thermal degradation at high temperatures. The definition of different classes of surface defects has traditionally relied on human expertise. This manual approach can be complex and time-consuming, with a sometimes subjective interpretation, particularly when the data studied contains several defects. Recent advances in artificial intelligence, machine learning and deep learning provide interesting opportunities for automated processing. Various experiments were carried out on a high-temperature tribological experimental platform to study the friction and wear of a 6082-T6 aluminium alloy on AISI H13 steel with an Arc-DLC coating. The study temperatures are between 300°C and 500°C and the sliding velocities are 0.5mm/s and 5mm/s. Two experimental databases were generated from interferometric measurements and SEM images. The study compares machine learning and deep learning approaches, different supervised algorithms classically used in Machine learning, and attempts to understand poor predictions. Finally, the results obtained by Deep learning are compared and analyzed for polluted and unpolluted databases.La fabrication écoresponsable privilégie le formage sans lubrifiant afin de réduire les coûts et minimiser l'impact environnemental. Dans le cas du formage à haute température des alliages d'aluminium, cette approche qui se traduit par un contact direct entre la pièce et les outils, entraîne un transfert de matière et des défauts de surface. Bien que les revêtements en carbone amorphe, tels que le DLC, atténuent ces problèmes, ils restent vulnérables à l'usure mécanique et à la dégradation thermique à haute température. La définition des différentes classes de défauts de surface repose classiquement sur l’expertise humaine. Cette approche manuelle peut s'avérer complexe et chronophage, avec une interprétation parfois subjective, en particulier lorsque les données étudiées présentent plusieurs défauts. Les avancées récentes en intelligence artificielle, particulièrement en apprentissage automatique et profond, fournissent des voies intéressantes pour un traitement automatisé. Différentes expérimentations ont été menées sur une plateforme expérimentale tribologique à haute température pour étudier le frottement et l'usure d'un alliage d'aluminium 6082- T6 sur un acier AISI H13 avec un revêtement Arc-DLC. Les températures d’étude sont comprises entre 300°C et 500°C et les vitesses de glissement sont 0.5mm/s et 5mm/s. Deux bases de données expérimentales ont été générées à partir de mesures par interférométrie et d’images MEB. L’étude permet de comparer les approches par apprentissage automatique et profond, différents algorithmes supervisés utilisés classiquement en apprentissage automatique et s’attache à comprendre les mauvaises prédictions. Enfin, une comparaison et une analyse des résultats obtenus par apprentissage profond pour des bases de données polluées ou non sont réalisées
Mechanical Design and Assembly of a Modular Educational Robot Using APIRO Components
No full textInternational audienceThis paper presents a modular Cartesian robot for educational use, built using APIRO mechanical components and controlled via a browser-based interface hosted on an ESP32 microcontroller. The system enables students to explore mechanical assembly and axis control through hands-on interaction without additional software or internet access. A structured task design supports learning of motion along the X, Y, and Z axes. To improve control safety and repeatability, a hybrid open-loop method was implemented, combining homing routines with software-defined soft limits. While full automation is not yet integrated, the robot offers a scalable, low-cost platform for step-by-step learning in robotics. Testing confirmed stable, repeatable joint motion suitable for classroom and prototyping environments
Tunable Topological Directional Supercoupler and Applications in THz On‐Chip Communication
No full textInternational audienceA photonic directional coupler plays a critical role in photonic integrated circuits and communication technologies, facilitating precise power distribution for multi-channel data routing and transmission. However, conventional directional couplers face limitations in further optimizing the footprint and efficiency due to the large waveguide bending curvature and momentum mismatch between coupled waveguides. Here, a topological directional supercoupler is presented on a valley Hall silicon photonic crystal chip that achieves the shortest coupling length of 0.27 wavelength (λ) within a coupling area of 0.06λ2. Broadband phototunable coupling ratios are experimentally demonstrated over a bandwidth of 24 GHz with a tuning range of up to 72.8%. The dual-channel terahertz on-chip communication, each with a 50 Gbps data rate, further verifies the signal directional routing performance. The topological directional supercoupler provides a compact platform for topological integrated systems, promising applications in terahertz communication, interferometers, antenna arrays, and photonic neural networks
L'apport des évaluations informelles dans la méthodologie de conception collaborative d'un dispositif de rééducation impliquant ergothérapie et informatique
No full textInternational audienceThis paper presents the methodology followed in the TeMaCo project, which aims to develop a digital tool designed to make rehabilitation sessions more engaging and enjoyable. The system must be accepted both by the occupational therapist leading the session and by the patient undergoing rehabilitation. To achieve promising results in terms of acceptability, the design process involved 184 participants in feedback collection and evaluations, and over 1,000 people in activity trials conducted during four scientific or public events. This paper highlights how informal evaluations add value to the co-design process of a rehabilitation tool. By informal evaluation, we refer to an assessment with a fixed protocol which, unlike controlled evaluations that we qualify as formal, takes place during public events where visitors are invited to participate. Each informal evaluation contributed to refining the system to better meet user needs and to building a scientific evaluation whose results are promising. Looking ahead, future work will be carried out with occupational therapists to prepare a rehabilitation protocol integrating the system.Cet article présente la méthodologie suivie dans le projet TeMaCo dont l'objectif est de proposer un dispositif numérique permettant de rendre les séances de rééducation plus ludiques. Ce dispositif doit être accepté par l'ergothérapeute qui gère la séance et par la personne en rééducation. Pour obtenir un résultat prometteur en termes d'acceptabilité, le processus de conception a impliqué 184 personnes dans des recueils d'avis et des évaluations et plus de 1000 personnes pour essayer des activités, lors de 4 événements scientifiques ou grands publics. Cet article montre comment les évaluations informelles représentent une plus-value dans le processus de co-conception d’un dispositif pour la rééducation. Nous entendons par évaluation informelle, une évaluation avec un protocole fixe, qui, à la différence des évaluations en situation contrôlée quenous qualifions de formelles, se déroule lors d’événements publics, où les visiteurs sont invités à participer. Chacune des évaluations informelles a permis de concevoir un dispositif répondant au mieux au besoin et de construire une évaluation scientifique dont les résultats sont prometteurs. En perspective, un travail sera mené avec les ergothérapeutes pour préparer un protocole de rééducation utilisant le dispositif
Performance of Long Range-Frequency Hopping Spread Spectrum (LR-FHSS) For LoRaWAN Satellite Communication: https://journal.umy.ac.id/index.php/eist/article/view/26431
No full textInternational audienceSome factors that need to be developed in the LoRaWAN satellite communication system are using LR-FHSS (Long Range-Frequency Hoppong Spread Spectrum) to increase resistance to frequency interference and jamming, with the technique of using a small bandwidth per channel and operating on the same spectrum. With LR-FHSS devices on Earth can communicate with satellites that have relatively many movements. LR-FHSS uses 137 kHz bandwidth which is divided per channel around 488 Hz, with coding rates of 1/3 and 2/3 and separately modulated headers and payloads, and hop distance is a range of 3-50 kHz. LR-FHSS implementation is for monitoring hard-to-reach areas such as oceans, mountains, deserts, and others, as well as logistics tracking and asset management. LR-FHSS LoRaWAN uses RP2-1.0.1 which is the LoRa Alliance standardization for satellite communication. This research shows the Frequency Hopping Pattern for each device, the graph shows that there are 3 devices, devices 1, 2, and 3, which are spread over the free frequency channel between 0.0 and 17.5 with time slots 0 to 90. CR 1 with Frequency Hopping produces the fastest Time-on-air (ms) of 2 ms, and CR 2/3 with Frequency Hopping 3 ms, this is the best setting to produce the fastest ToA
Roughness multiscale analysis of wear mechanisms in polymer abrasion
No full textInternational audiencePolymers are essential for the automotive industry, the aircraft industry and medical devices due to their combination of lightness and strength. However, performance of polymers might decrease with their degradation and wear studies become necessary to ensure both usefulness and safety during their operation time. This article studies the physical phenomena involved in the abrasion of nine common polymers using surface topography. Polymer disks are cut from polymer rods, followed by a mirror-polishing and then by abrasion with silicon carbide abrasive papers from grades 80-4000. A white light interferometer is used to measure high-resolution over a large field-of-view topographies of the polymer disk surfaces thanks to stitching. To determine the scale of applications of physical phenomena involved in the abrasion process, four multiscale roughness decompositions are applied on topography and compared: the patchwork method, the box Sa method, the box Sz method and the motif method. All multiscale analyses have detected a cross-over separating micro and macro abrasion for all polymers and abrasive paper grades. A new parameter, the Abrasive Ratio Ar, is introduced, representing the ratio between the penetration depth of the abrasive grain into the polymer disk over the abrasive grain size. This parameter helps the identification of four abrasion wear mechanisms and their scale of applications: the hydrostatic limit stage (80 µm and higher), the strain hardening stage (30 µm - 80 µm), the localized adhesion stage (10 µm - 30 µm) and the grit size effect stage (10 µm and smaller)