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Bilan des activités 2024 de la plateforme de micro et nanotechnologies du LAAS-CNRS
No full textNational audienc
Meeting of EuronanoLab at ENRIS (Bolognia) : Experts group Thin Film session: Kick off for Thin Film european group
No full textInternational audienceThe steering committee of EuronanoLab requested the implementation of the kick-off of Thin Films. Pascal Dubreuil, along with Susana de Freitas and Matias Trujillo, co-organized the session of the expert group in person with oral presentations from national networks about ALD, CVD, ALD technics and all thin film materials . A program (meeting online, workshops) for the year 2025 was then presented and validated in the session
Hybridising photovoltaics and thermoelectrics: A detailed-balance analysis
No full textInternational audienceThe combination of photovoltaic and thermoelectric converters could potentially lead to an improvement in the efficiency with which solar energy is converted into electricity, thanks to the improved exploitation of the residual heat generated in the PV cells. Using the detailed balance formalism, we develop a simple model enabling to derive the ultimate efficiency limits of PV-TE systems on the basis of a restricted number of operating parameters, including the bandgap of the semiconductor materials used, the cell temperature and the concentration ratio of the solar flux to which the PV cells are subjected. It is shown that in the radiative limit, the added value of PV-TE systems remains relatively modest, with an improvement in the electrical power generated of the order of 5% relative to conventional PV systems, and up to 15% for CPV systems operating under concentrated solar flux. Secondly, the limited capacity of real photovoltaic cells to approach their own theoretical limits is taken into account. We demonstrate a substantial improvement in the performance of PV-TE systems incorporating realistic solar cells operating at only a fraction of their theoretical limit, compared with reference PV systems. The value of solar concentration, which provides an additional leverage in the quest for high temperatures, while mitigating the adverse effect of temperature on PV cell efficiency, is also highlighted. Finally, the paper discusses the practical limitations of the model and outlines the operating and material parameters that need to be taken into account in order to rigorously determine the added value of these systems compared with conventional PV modules
Physical optics modelling of eye displacement detection using self-mixing interferometry
No full textInternational audienceSelf-mixing interferometry is compact, sensitive and cost-effective solution over conventional interferometric methods for precise measurement in various applications. The numerical solution for synthesizing SMI signal and its analysis is discussed as per Lang and Kobayashi model under temporal steady state conditions. However, this numerical approach does not provide detailed information about SMI Signal such as 2D interferograms, and amplitude variation. This work investigates the potential of physical optics simulations to replicate real-world SMI signals compared to experimental measurements, with a specific focus on fringe frequency and amplitude. The results obtained are also compared with numerical method based on Lang and Kobayashi under steady state solution
Optimizing quasi-dissipative evolution equations with the moment-SOS hierarchy
No full textInternational audienceWe prove that there is no relaxation gap between a quasi-dissipative nonlinear evolution equation in a Hilbert space and its linear Liouville equation reformulation on probability measures. In other words, strong and generalized solutions of such equations are unique in the class of measure-valued solutions. As a major consequence, non-convex numerical optimization over these non-linear partial differential equations can be carried out with the infinite-dimensional moment-SOS hierarchy with global convergence guarantees. This covers in particular all reaction-diffusion equations with polynomial nonlinearity
Visual Assistance in VR-based Robot Control: Towards a Reproducible Evaluation Scenario
No full textNational audienceImmersive technologies enhance industrial applications by creating virtual representations of manufacturing environments and providing visual assistance for tasks. Most studies in the literature are based on ad hoc scenarios, making comparison across studies challenging. In this research, 99 participants controlled a remote industrial robot using a VR headset in a reproducible maintenance task. They performed the task under three conditions: without assistance (control), text-based assistance, or attentional cueing (highlighting objects). We manipulated task difficulty (easy versus difficult) and assessed performance based on completion time and failure rate. Results showed visual assistance significantly shortened task completion time, with findings discussed
A predictive coding framework for safe and versatile control of supernumerary robotic limbs
No full textRobotic supernumerary limbs (SLs) can enable humans to perform alone tasks requiring more than two hands. By increasing the number of the body's effective degrees of freedom, SLs could have a major impact on industrial and medical applications, and profoundly change the way humans interact with their environment. However, current SL usage is limited, with only specific applications and a lack of a comprehensive framework for versatile ubiquitous use. This limitation arises primarily from the intertwined challenges of ensuring safety and coordination between the natural limbs and SLs. This paper presents a novel framework for SL sensorimotor augmentation based on predictive coding, a process rooted in hierarchical neural structures that allow the brain to seamlessly manage coordinated complex actions. Our framework comprises three levels where each generates predictions for and receives prediction errors from the level below. The α-layer detects the user's movement intent and ensures safety through generated constraints. The β-layer controls actions and related sensory feedback. In this layer, we propose a novel general voluntary control (GVC) mechanism that offers a continuum between fully autonomous SLs behaviors and direct control, thereby allowing a user to control SLs with minimal cognitive effort. The γ-layer executes the SLs' control and handles their interaction with the body and the environment. For each framework component, we review relevant literature and illustrate implementation strategies that support safe and versatile SLs control. We further demonstrate, through systematic simulations, the usability and robustness of the proposed GVC mechanism, paving the way toward versatile human-SLs interactions
M2.2.3 - High-resolution laser ablation of a copper layer for the fabrication of 3D-printed MEMS and microsensors
No full textarticle soumis après conférence Eurosensor 2025International audienc
Detection of Dielectrically Heterogeneous 3D Multicellular Objects with Microwave Dielectric Spectroscopy
No full textInternational audienceMulticellular 3D biological models, also called spheroids or microtissues, are considered very promising for drug screening and cancer studies, as they integrate a structural heterogeneity and therefore exhibit a physiological complexity that closely mimics in vivo tissues. Such a model is usually characterized with optical techniques. These are very efficient but present however the implication of labels and high-cost equipment. To complete such methods, microwave dielectric spectroscopy presents attractive features, as it is non-invasive, label-free and rapid. To demonstrate its ability to evaluate 3D heterogeneous bio-models, a microwave biosensor suitable for the analysis of such bio-objects is evaluated. Three different types of elements with constitutional dielectric heterogeneity are used, spheroids with living HepG2 cells, polystyrene beads and the combination of these two models considered as hybrid spheroids. A clear discrimination of the different model categories is obtained, demonstrating the ability of the microwave sensing technique to detect a 3D bio-object with heterogeneous dielectric structuration