Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

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Near-field focusing techniques in inhomogenous media at millimiter wave

Département Systèmes (LETI)

Laboratoire Antennes, Propagation, Couplage Inductif

01-10-2021

SL-DRT-21-0378

antonio.clemente@cea.fr

Communication networks, IOT, radiofrequencies and antennas (.pdf)

In a huge number of applications such as wireless power transfer (WPT), microwave imaging, industrial control, etc., it is required to collimate, form or focus the electromagnetic radiation in a specific region of the space. Sometimes, this region could be located in the near-field region of the radiating element or surface. In this case, it is referred to as a near-field focused system. With the development of the future ?Beyond 5G? and 6G communication systems, the necessity to focus the radiating beam in the near-field region could be also required in the case of the reconfigurable intelligent surfaces (RIS). These kind of devices, when composed of reconfigurable elements, can be deployed to manipulate the electromagnetic waves and dynamically control and adjust the properties of the propagation channel. Eventually, near-field focusing could be also applied to future medical imaging systems at microwaves. These devices require focusing and collimating the electromagnetic energy in the human body tissues in order to diagnose, monitor and/or treat specific pathologies. In this context, near-field focusing can be used to improve the resolution of the imaging system by optimizing the energy transfer/transmission. The first objective of this thesis is to develop specific numerical tools for the synthesis, design and optimization of near-field focused systems in non-homogeneous media. These techniques will be developed by considering the electromagnetic properties of the media. The synthesis of the aperture field will be done considering modal expansion of the field and the potential vectors theory. After this phase, the synthesis and optimization procedures will be used to design a near-field focused antenna system operating at millimeter and/or sub-THz frequencies (30 - 300 GHz). These antennas will be manufactured and characterized in near-field test ranges. Measurements will validate the developed models for flat radiating apertures in specific scenarios. The possibility to perform measurements in a real applicative context (e.g. cancer detection) will be also considered.

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Lensless imaging and artificial intelligence for rapid diagnosis of infections

Département Microtechnologies pour la Biologie et la Santé (LETI)

Laboratoire Systèmes d'Imagerie pour le Vivant

01-10-2020

SL-DRT-21-0380

caroline.paulus@cea.fr

Artificial intelligence & Data intelligence (.pdf)

The objective of the thesis is to develop a portable technology for pathogen identification. Indeed, in a context of spread of medical deserts and resurgence of antibiotic-resistant infections, it is urgent to develop innovative techniques for rapid diagnosis of infections in isolated regions. Among optical techniques for pathogen identification, lens free imaging methods draws attention because they are the only ones currently able to offer simultaneous characterization of a large number of colonies, all with low-cost, portable and energy-efficient technology. The objective of the thesis is to explore the potential of lensless imaging combined with artificial intelligence algorithms to identify bacterial colonies present in a biological fluid. The thesis will aim to optimize the sizing of the imaging system (sources, sensors) and to study image processing and machine learning algorithms necessary for colony identification. Two cases of clinical applications will be studied.

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Multiphysical design of high-voltage power semiconductor modules for renewable energy conversion

Département des Technologies Solaires (LITEN)

Laboratoire Systèmes PV

01-09-2021

SL-DRT-21-0387

jeremy.martin@cea.fr

Solar energy for energy transition (.pdf)

Research and development around silicon carbide (SiC) power semiconductors provides samples that can withstand voltages up to 15kV. These devices switch at very high speeds (e.g. 120kV / µs for a 10kV SiC MOSFET or 180kV / µs for a 15kV SiC IGBT). Overall, the performances of these semiconductors are exceptional, and drastically reduces the switching losses compared to Silicon equivalents. The implementation of these switches is on the other hand very delicate and calls upon methodologies of multiphysics design in transversal disciplinary fields. It is, from the scientific literature addressed a number of scientific and technological obstacles that we can list: -Minimization of parasitic inductors of power modules (<5nH) -Integration of EMC shielding to collect disturbing impulse currents -Cooling of SiC chips so the size is very small compared to a Si equivalent -Management of partial discharges and dielectric materials -Influence of dV / dt on the aging of materials (in DC, at 50Hz, and in pulse) -Reflection phenomena (electromagnetic wave) The proposed work consists of studying and proposing a power module architecture integrating innovations making it possible to address the implementation of SiC chips up to 10kV. The teams from the CEA in Toulouse specialists in high power 3D packaging will provide their skills in assembly technologies for the production of complex power modules. The CEA teams at INES campus (Nat. Inst. of Solar Energy)located at the Bourget du Lac (Savoy) will provide their high voltage measurement and prototyping means as well as their knowledge in power module design (finite element simulation). Researchers from G2ELAB in Grenoble in cooling of power modules and dielectric science will use their knowledge as well as their experimental platforms.

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Oscillating neurons for computational optimization and associative memory

Département Composants Silicium (LETI)

Laboratoire d'Intégration des Composants pour la Logique

01-10-2021

SL-DRT-21-0393

louis.hutin@cea.fr

Artificial intelligence & Data intelligence (.pdf)

Hopfield networks are a type of recurring neural network particularly well-suited to content-addressable associative memory functions. By giving its elements the ability to fluctuate at will, they can be adapted to efficiently solving NP-hard combinatorial optimization problems. Such problems, for which finding exact solutions in polynomial time is out of reach for deterministic Turing machines, find many applications in diverse fields such as logistic operations, circuit design, medical diagnosis, Smart Grid management etc. The frame of the proposed project is the search for hardware accelerators for Artificial Intelligence. In particular, we consider the use of injection-locked oscillators as neurons (ILO). The goals will be the design, fabrication and demonstration of such networks, featuring binary phase-encoded neurons coupled by adjustable synaptic weights, to carry out associative memory (e.g. pattern recognition) or combinatorial optimization tasks (ex: max cut, graph coloring,...).

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Synthesis and study of chiral organic materials for charge transport in organic semiconductors

Département d'Optronique (LETI)

Laboratoire des Composants Emissifs

01-10-2021

SL-DRT-21-0395

benoit.racine@cea.fr

Photonics, Imaging and displays (.pdf)

The detection and manipulation of the polarized light is very attractive, in particular because of the interest in using circularly polarized light (LCP) in many areas of societal importance such as technologies display, information transmission, cryptography, bio-medical imaging or even the detection of chiral molecules of pharmaceutical interest. Due to their ability to interact specifically with an LCP and to modulate its polarization, chiral molecular materials stand out as an element of choice for exploring these innovative applications and considering new potential in organic electronics. In addition, the specific property of chiral molecules to induce electronic spin selectivity in the conduction of electric current (CISS effect for Chiral Induced Spin Selectivity) also opens up opportunities in the field of organic spintronics. Consequently, the synthesis of innovative pi conjugated chiral semiconductors, presenting an easy modulation of their physicochemical properties and the integration of these materials in optoelectronic devices of the OLEDs, OPDs or OFETs type is of interest both fundamental and 'application. The thesis project will be done in collaboration with a CNRS chemistry laboratory in Rennes, France, and the LCEM laboratory (at CEA / LETI, Grenoble, France) specialized in organic semiconductors. The objectives of the thesis student will be to synthesize new chiral organic charge transporters and to characterize their photophysical (absorption and emission) and opto-electronic properties. The most promising molecules will be integrated into OLEDs and OPDs devices. The photophysical synthesis and characterization part (circular dichroism spectrometer, non-polarized and circularly polarized luminescence spectrometer, PER, etc.) will be carried out at the CNRS chemistry laboratory. The integration of molecules in OLEDs and OPDs devices will be done in the LCEM laboratory where the deposition equipment (PVD chamber for organic materials) and the opto-electronic characterization means (IVL, C (V), TLM, Photocurrent, hall effect, etc.).

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Study, evaluation and validation of the performance of a boron measurement system using neutron absorption

Département Métrologie Instrumentation et Information (LIST)

Laboratoire Capteurs et Architectures Electroniques

01-10-2021

SL-DRT-21-0397

adrien.sari@cea.fr

The concentration of boron in the primary-circuit fluid of a nuclear reactor must be finely controlled in order to guarantee its safety. Indeed, an excursion of the boron concentration could lead to a risk of criticality. An online nuclear-measurement system is therefore required to monitor the boron concentration in the primary reactor fluid. Such a system is commonly referred to as a "boronmeter". The proposed thesis subject is made up of three lines of research. The first line aims to study by Monte Carlo simulation, and then conceptualise and theoretically formalise the behaviour of the two main performance criteria (counting rate and contrast) of the boronmeter under the influence of its different characteristics. The second line of research aims at evaluating and experimentally validating the interpretation of the effects brought into play within the boronmeter and the theoretical concepts formulated. This experimental work will be carried out in close collaboration with the Laboratoire National Henri Becquerel (LNHB). The third line of this thesis aims to conceive an innovative boronmeter designed to measure the boron concentration in the primary fluid as close as possible to the core of the nuclear reactor. Such a system would make it possible to identify as quickly as possible an anomaly in the boron-concentration value at the reactor core. However, the constraints imposed by such a measurement environment will have to be taken into account, and a suitable measurement methodology will be developed. Different approaches to temperature and fluid-flow compensation will be the subject of in-depth investigations.

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