Composant électronique | EPFL Graph Search

Un composant électronique est un élément destiné à être assemblé avec d'autres afin de réaliser une ou plusieurs fonctions électroniques. Les composants forment de très nombreux types et catégories, ils répondent à divers standards de l'industrie aussi bien pour leurs caractéristiques électriques que pour leurs caractéristiques géométriques. Leur assemblage est préalablement défini par un schéma d'implantation d'un circuit électronique. Définition Composants actifs alt=Un transistor, composant actif, boîtier ouvert.|vignette|Un transistor, composant actif, boîtier ouvert. Un composant actif est un composant qui permet d'augmenter la puissance d'un signal , La puissance supplémentaire est récupérée au travers d'une alimentation. On peut citer en majorité des composants semi-conducteurs, on y classe : transistor, circuit intégré. Il existe généralement une connexion électrique interne entre deux bornes du composant où le courant et la tension sont de même signe

Thermal management of components for high energy physics experiments and space applications

Timothée Robert Sophus Frei

High-energy physics (HEP) experiments and space missions share a common challenge: thermal management in harsh environments. The severe constraints in both fields make cooling of electronic components a major design concern. This thesis aims to develop high thermal conductivity, radiation hard devices for thermal management in HEP and space application with the help of micro-technologies.Continuous advances in micro-engineering have opened the door to the development of smaller and more efficient cooling devices capable of handling increasing power densities with minimum mass and volume penalties. In this respect, previous works have focused on the use of microchannels etched in single crystal silicon (ScSi) wafers to circulate a cooling fluid. However, whilst this technique represents the state-of-the-art for thermal management of silicon detectors, it poses several challenges, particularly those associated with the fluidic interconnections, compatibility with high operating pressures and coverage of large areas. A cooling scheme relying on two independent fluidic loops is proposed to overcome these limitations. The two cooling loops, referred to as the primary and the secondary cooling loops (i.e. PCL and SCL respectively), are connected through thermal and mechanical interfaces but do not share any fluidic interface. Both circuits work together to remove heat and control the temperature of multiple electronic components. The SCL transfers the heat generated at the source to the PCL, which transports it further away and dissipates it to the environment.The present thesis investigates the use of micro-oscillating heat pipes (uOHPs) to implement the secondary cooling loops. These devices offer great potential, particularly if embedded in silicon substrates. However, a better understanding of the mechanisms responsible for their self-actuated, two-phase flow is essential to produce high performance devices which meet the stringent requirements of particle detectors and spacecraft. Two types of dual-diameter uOHPs were microfabricated: the first version used a glass wafer to close trenches etched in a silicon substrate, while an all-silicon construction was adopted in the second type. The thermocompressed interface used to bond the two silicon wafers yielded excellent pressure resistance. The thermal performance of the of uOHPs was studied for different working fluids, charging ratios, orientations, and heat inputs, taking advantage of the transparent cover in the glass devices to monitor the two-phase flow for the different conditions. The results revealed that the performance of the proposed uOHPs was orientation-independent. Furthermore, under certain conditions the equivalent thermal conductivity of acetone-charged devices exceeded that of an equivalent copper strip.Finally, an innovative technique for charging and sealing the micro-cooling heat pipes was developed. It offers a low-volume, small-footprint solution to enclose working fluids in the devices. The proposed technique, which relies on a compressed Indium preform to seal the inlet charging port, yield very good leak-tightness results.

EPFL2021

Computational Analysis and Methods for Electromagnetic Exposure Limits, Antenna Optimization and Cell Phone Design

Chen Xi Lin

In recent years, the advancements of wireless technologies have led to rapid developments in the field of telecommunication, power delivery and bio-medical applications. During the evolution of a wireless technology, the electromagnetic compatibility (EMC) between a radiating source (e.g., an antenna) and nearby active or passive elements (e.g., a closely integrated electronic component or a human body) often introduces challenging design requirements. This thesis focuses on the applications of state-of-the-art computational electromagnetic compatibility (CEMC) techniques in multidisciplinary engineering design tasks, with an emphasis on computational bio-electromagnetic compatibility (CBEMC). The analyses reported in this thesis span practical applications from power frequency (Hz) to radio frequency (GHz), providing research outcomes which significantly benefit the understandings of low-frequency human body exposure safety and radio-frequency antenna integration and optimization. The research aspect of the thesis is initiated with a thorough review of the existing low-frequency exposure safety guidelines recommended by international regulatory committees. The subsequent analyses suggest essential scientific basis for the update and revision of the existing exposure limits. Practical exposure scenarios (e.g., magnetic resonant wireless power transfer) are investigated with novel assessment techniques. Subsequently, a computer-aided optimization scheme based on network-distributed genetic algorithms is applied to highly detailed numerical mobile phone model and human body phantoms. The investigated optimization technique is proven to be superior than traditional empirical approaches. Finally, the CEMC techniques are applied in the context of non-dosimetry related engineering design environment by investigating the integration of a miniature loudspeaker (acoustic component) and a mobile device antenna (radio frequency component). Based on simulation and measurement data, the coupling mechanisms are determined to establish the fundamental design guidelines for optimum antenna-speaker co-existence and performance. In summary, this thesis details several novel applications of CEMC in the most stringent and complex industrial design environments. The presented research findings serve as indispensable basis for future research oriented towards the exposure-compliant and electromagnetic- compatible designs for novel wireless technologies.

EPFL2013

Highly Stretchable Flame-Retardant Skin for Soft Robotics with Hydrogel-Montmorillonite-Based Translucent Matrix

Hritwick Banerjee

Flame-retardant coatings are crucial for intelligent systems operating in high-temperature (300-800 degrees C) scenarios, which typically involve multi-joint discrete or continuous kinematic systems. These multi-segment motion generation systems call for conformable yet resilient skin for dexterous work, including firefighting, packaging inflammable substances, encapsulating energy storage devices, and preventing from burning. In fire scenes, a flame-retardant soft robot shall protect integrated electronic components safely and work for navigation and surveillance effectively. Here, we establish fire-resistant robotic mechanisms with montmorillonite (MMT)-biocompatible hydrogel skin, offering effective flame retardancy (similar to 78 degrees C surface temperature after 3 min in fire) and high post-fire stretchability (similar to 360% uniaxial tensile strain). Fatigue test results in the MMT-hydrogel polymer matrix to portray a change in post-fire energy consumption of similar to 21% (between the first cycle and the 200th cycle), further indicating robustness. MMT-hydrogel synthetic skin medium is then applied to everyday household items and electronics, offering appealing protections in fire scenes (

MARY ANN LIEBERT, INC2021