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High Round-Trip Gain Piezoelectric-Capacitive Hybrid Micromachined Ultrasonic Transducer Based on Anodic Bonding Technology
No full textInternational audienceIn this work, a piezoelectric-capacitive hybrid micromachined ultrasonic transducer (HMUT) with a high round-trip gain was developed to achieve superior pulse-echo imaging performance. Initially, an equivalent circuit model (ECM) and a finite element model (FEM) were constructed to design and simulate the HMUT cell. A patterned etching technique for the piezoelectric layer was incorporated into the HMUT design. Simulation results indicated that the round-trip gain of the HMUT with patterned piezoelectric layer is 33 dB higher than that of the piezoelectric micromachined ultrasonic transducer (PMUT) and 3 dB higher than that of the capacitive micromachined ultrasonic transducer (CMUT). One of the innovative aspects of this technique is its ability to fabricate vertically stacked PMUT and CMUT. Based on anodic bonding technology, prototypes of 3 MHz PMUT, CMUT, and HMUT were fabricated on the same substrate. Finally, an electric impedance test and pulse-echo test were conducted. Experimental data confirmed that the HMUT exhibits higher round-trip gain, consistent with the simulation results. The successful fabrication of these prototypes demonstrates the feasibility of integrating multiple ultrasonic transducers on a single platform, enhancing the device’s compactness and versatility. Furthermore, it opens new avenues for the development of high-quality ultrasonic imaging
Miniaturized Intelligent Actuators Enabling Active Endoscopic Navigation
No full textInternational audienceThis poster presents the development of intelligent actuators for active micro-endoscopes, designed to enhance surgeons’ diagnostic capabilities during operations. The proposed system enables real-time adjustment of the viewing angle without physically moving the endoscope, thus contributing to less invasive procedures and minimizing the need for larger medical tools. The research addresses the challenge of creating a thin, flexible, and actively controlled endoscope by exploring the integration of the smallest commercially available image sensors and micro-actuators. Special attention is given to the miniaturization constraints and the biocompatibility of components in the targeted surgical environment.Ce poster présente le développement d'actionneurs intelligents pour micro-endoscopes actifs, conçus pour améliorer les capacités de diagnostic des chirurgiens pendant l’opération. Le système proposé permet d’ajuster l’angle de vue en temps réel sans déplacer physiquement l’endoscope, favorisant ainsi des interventions moins intrusives et limitant l’utilisation d’outils médicaux encombrants. La recherche traite du défi de concevoir un endoscope actif, fin et flexible, en intégrant les plus petits capteurs d’image et actionneurs disponibles sur le marché. Une attention particulière est portée aux contraintes de miniaturisation ainsi qu’à la biocompatibilité des composants dans l’environnement chirurgical ciblé
Motivational factors influencing the choice of oncology as a specialty among French medical students
No full textInternational audienceBackground: There is limited data regarding what motivations are behind the choice of oncology (both medical oncology and radiation oncology) as a specialty among medical students. Therefore, the aim of this study is to identify the factors that motivate medical students to choose oncology as a specialty.Methods: Medical students of classes 2022 and 2023 in the Universities of Lille and Amiens (North of France) were enrolled in a quantitative online survey. Chi-square automatic interaction detection (CHAID) and binary and multiple linear regressions were performed to identify the factors that determine the choice of specialty among the students.Results: Among 563 respondents (response rate: 45%) who participated in the survey, 14, 13, and 14 were considering oncology as their first (2.5%), second (2.3%), and third (2.5%) specialty choices, respectively. The CHAID analysis retained two factors: "rotation in the medical oncology unit" (p < .0001) and "identification with a physician practicing the desired specialty" (p = 0.049). The factors identified in the multivariate regression analysis (weighted according to first, second, or third choices) differed according to sex. In men, rotation in a radiation oncology unit (β = 0.190; p < 0.001) or a medical oncology unit (β = 0.227; p = 0.010) and interest in fundamental research (β = 0.063; p < 0.001) were positively associated with choosing oncology as a specialty, whereas working in rural areas (β=-0.094; p = 0.014) was negatively associated with choosing oncology as a specialty. In women, rotation in a medical oncology unit (β = 0.289; p < 0.001), interest in cultivating a long-term relationship with patients (β = 0.129; p < 0.001), and interest in a hospital-based career (β = 0.214;p < 0.001) were positively associated with choosing oncology as a specialty; whereas desire to see the results of treatments quickly (β=-0.143; p = 0.018) and working in rural areas (β=-0.153; p = 0.006) were negatively associated with choosing oncology as a specialty.Conclusions: Experience during hospital rotations plays a crucial role in the specialty choices made by medical students. The motivations behind choosing oncology as a specialty differ according to gender. Intrinsic motivations (interests in fundamental research or in cultivating a long-term relationship with patients) and contextual factors (rural life or interest in a hospital-based career) influence the specialty choices of medical students
Dynamic switching of ferrocene and plasmonic interactions in Au/self-assembled monolayer/single Ag nanocube molecular junctions
No full textInternational audienceWe report the redox switching of ferrocene moieties embedded in a double tunnel barrier plasmonic cavity fabricated from a click-chemistry self-assembled monolayers of ferrocenyl-alkylthiol on ultra flat gold surfaces, connected to a single poly(vinylpyrrolidone) capped silver nanocube, AgNC, which is contacted by the tip of a conductive-AFM to study the electron transport properties in the dark and under light irradiation at the plasmonic resonance wavelengths. We observe a dual behavior in the current-voltage (I-V) characteristics in the dark: a large hysteresis loop at positive voltages and an hysteretic negative differential conductance (NDC) at negative voltages, due to the redox switching of ferrocene between its oxidized (Fc+) and neutral (Fc0) states. The I-V curves are analyzed by a generalized combined Marcus-Landauer model. We determine the highest occupied molecular orbital of the Fc+ and Fc0 states at 0.54 and 0.42 eV below the Fermi energy, respectively, with a weak reorganization energy < 0.1 eV upon switching. Under plasmonic excitation, the hysteresis and NDC behaviors are no longer observed and the I-V characteristics of the Au-ferrocenyl-alkylthiol/AgNC junctions become similar to Au-ferrocenyl-alkylthiol SAMs. A virtual molecular orbital due to the plasmon-induced coupling (fast electron transfer) between the two redox states of the Fc is determined at 0.46 eV. This dynamic behavior opens perspectives in artificial synaptic devices for neuromorphic computing with the additional function to turn on/off this synaptic behavior on-demand by light
PEPR ADICT: Fabrication of RF switches based on MoS and WS
No full textNational audienceIn the framework of the ADICT project, the partner IEMN-CARBON aims to produce components based on 2D materials [1-3], for targeted PEPR projects. The aim is to extract their electrical properties and propose applications for high-frequency analogue electronics.The first components to be explored are RF switches based on 2D materials.Our work has led us to develop technological processes that are compatible with those of our partners (CEA Leti). The material used is MoS2 by ALD (Atomic Layer Deposition) growth, requiring a wet or dry transfer step. The growth and the fabrication process are managed on a 200 mm silicon substrate.This approach will be compatible with materials obtained by MBE (Molecular Beam Epitaxy) growth.A second approach has been developed with our partners at LAF, where 2D materials (WS2) are obtained by PLD (Pulse Laser Deposition) growth, requiring no transfer step, given the lower thermal budget.The performance of the devices obtained is in line with the simulations carried out at IEMN. The performances obtained are already state-of-the-art for this type of component
Evaluating the Impact of Sampling Strategies on Classification Accuracy in Point-MAE for Point Cloud Classification
No full textInternational audiencePoint-MAE is a recently introduced technique for deep learning on point cloud data, and prior research has demonstrated the significant impact of pretraining datasets on the classification downstream task performance. Another critical factor in working with point cloud data is the sampling method and the number of sampling points used. This paper explores different sampling techniques for point cloud data, with a focus on farthest point sampling, as employed in Point-MAE. In this study, Point-MAE is pretrained on two datasets using varying numbers of sampling points (512, 1024, and 2048). Each pretrained model is then fine-tuned with the same sampling densities on four datasets. Results indicate that higher sampling points generally improve classification accuracy. However, pretraining on ModelNet40 with 512 sampling points and finetuning on ScanObjectNN PB_T50_RS variant achieved a classification accuracy of 92.72%. These findings highlight the importance of selecting an optimal pretraining dataset and sampling density based on dataset complexity
Removal of Ni2+ and Cd2+ from aqueous solutions by bionanosorbents: Isotherm, thermodynamic and mechanistic studies
No full textInternational audienceThe present work presents the efficiency and the limit in using bionanosorbents (cellulose, chitin and modified chitin nanocrystals) for the sorption of metal ions M2+ (M = Ni and Cd) in batch systems. Bionanosorbents were extracted from plants and shrimp shells, two available and low-cost materials. If cellulose and chitin nanocrystals did not efficiently remove metals in the experimental conditions of this work, the surface-modified chitin exhibited enhancement for the Ni2+ and Cd2+ adsorption capacity than original chitin nanocrystals. The Langmuir and Freundlich models fitted well to the experimental data from which the maximum adsorption capacity was 139.2 mg Ni g-1 and 38.4 mg Cd g-1. Regarding the Gibbs free energy and the Hall parameter, the sorption of Ni2+ and Cd2+ were spontaneous and favourable for pH around the neutrality. This corroborates the examination of IR spectra of oxidized chitin nanocrystals before and after the sorption process from which the metal removal mechanism was mainly attributed to the formation of complexes and ion exchanges of the bionanosorbent and metal ions. Element mappings of the bionanosorbents after sorption revealed a homogeneous distribution of Cd(II)
Potential of Bio-Sourced Oligogalacturonides in Crop Protection
No full textInternational audienceDuring plant development or interactions with pathogens, modifications of the plant cell wall occur. Among the enzymes involved, pectinases, particularly polygalacturonases (PGases), play a crucial role in the controlled hydrolysis of cell wall polysaccharides, leading to the formation of oligogalacturonides (OGs). These pectin-derived fragments act as key elicitors of plant defense responses, stimulating innate immunity and enhancing resistance to pathogens by modulating the expression of genes involved in immune responses and inducing the production of defense compounds. OGs are of particular interest for plant protection as a natural alternative to conventional phytosanitary products as they can be obtained through chemical, thermal, or enzymatic degradation of plant biomass. In a sustainable approach, agricultural by-products rich in pectin, such as citrus peels, apple pomace, or sugar beet pulp, offer an eco-friendly and cost-effective alternative for OG production. Thus, the current review aims to (i) update the state of the art about the different methods used to produce OGs, (ii) explore the potential of OGs as bio-based biocontrol molecules, and (iii) examine the relevance of new pectin sources for OG production
Nanoconfinement‐Induced Electrochemical Ion‐Solvent Cointercalation in Pillared Titanate Host Materials
No full textInternational audienceAbstract Electrochemical ion‐solvent cointercalation reactions are an avenue to reach improved kinetics compared to the corresponding intercalation of desolvated ions. Here, we demonstrate the impact of different structural pillar molecules on the electrochemical Li + intercalation mechanism in expanded hydrogen titanate (HTO) electrode materials. We show that interlayer‐expansion of HTO with organic pillars can enable cointercalation reactions. Their electrochemical reversibility is drastically improved when non‐cross‐linking pillars are employed that expand and separate the host material's individual layers, underlining the impact of the electrochemo‐mechanics of the nanoconfined interlayer space. This pillared HTO structure results in an increased Li + storage capacity and reversibility compared to pristine HTO. We derive structural models of the pillared HTO host materials based on combined experiments and theoretical calculations, and employ electrochemical operando experiments to unambiguously demonstrate the nanoconfinement‐induced cointercalation mechanism in pillared HTO electrode materials. The work demonstrates the potential of nanoconfined pillar molecules to modify host materials and enable highly reversible cointercalation reactions with improved capacity and kinetics