Development of a mechanical energy harvester based on a rotating machine architecture with permanent magnets
This Post-doc offer will be aimed at developing energy harvesters, and more especially electromagnetic energy harvesters with an operation mode close to the one of rotating machines with permanent magnets. The post-doc applicant will have a background in electrical engineering and an experience in rotating machines design, ideally, with permanent magnets.
The missions of the Post-doc applicant will be to:
1) Imagine and design small-scale innovative energy harvesters by exploiting the techniques used in rotating machines.
2) Model and optimize the devices
3) Characterize the systems
4) Participate to the industrialization process
Bio-compatible, bio-resorbable microbatteries for medical applications
In the framework of its activities dedicated to embedded micro-batteries, LETI initiates prospective research in the field of micro-batteries for medical applications, and in particular as energy power sources for implantable micro-devices. In this context, a collaborative project, including LETI labs and an academic Partner (ICMCB, Bordeaux), is aiming at designing, manufacturing and studying prototypes of bio-resorbable primary microbatteries.
The main tasks will include (i) a contribution to the design of the thin film electrochemical cell by the selection of adequate biocompatible materials (able to generate the targeted electrical power, corrodible and able to solubilize in the body), (ii) the manufacture of the cell constituents (electrodes, electrolyte, substrate) as thin films (sputtering, electrochemical plating, doctor blade coating) and their characterization,(iii) the achievement of full prototype cells and the study of their in vitro behaviour.
The work will be carried out at ICMCB (Bordeaux) in a joint CEA/ICMCB team, in collaboration with LETI labs in Grenoble.
Optimisation of the monolithic cascode device based on GaN/Si MOS-Channel HEMT technology
In order to adress the requirements of power conversion in the field of electrical vehicule or photovoltaics, high performance GaN on Silicon power devices need to be developped. Such power devices must fulfill agressive specifications in terms of threshold voltage (> 2V), nominal current (100-200A), breakdown voltage (650 and 1200V) and stability (low "current collapse", low hysteresis). Discrete cascode configuration, consisting in a combination of a low voltage E-mode Silicon die and a hihg voltage D-mode GaN/Si die in a single package, has been developped by different laboratories and companies to adress this need (Transphorm, On-Semi, NXP, IR…). However, this approach has some drawbacks like parasitic inductances, device pairing, need of additionnal protection devices, cost, temperature limitation due to the Si die...
The monolithic cascode is a very compact version of the cascode configuration that will allow to avoid those problems but also to improve the performance of E-mode devices developped at Leti (MOS-channel HEMT). Indeed, some actors in the field of GaN power devices already use this configuration with another E-mode technology (p-GaN gate).
Monolithic cascode device has been demonstrated recently by CEA-Leti in the frame of a PhD thesis (2014-2016) on the basis of the 200mm GaN/Si, CMOS compatible, MOS-channel HEMT technology. The aim of this post-doc is to optimize the monolithic cascode structure in terms of On-state resistance, Figure Of Merit, switching losses and high switching frequency capability in order to meet the specifications of our industrial partners.
Frequency tunable elastic plate wave resonators and filters
The increasing number of frequency bands having to be dealt with in mobile phone systems require a huge number of band pass filters in such systems. In this context, the capability to provide frequency tunable resonators and filters is seen as a key enabling element in future wireless transmission systems.
CEA-LETI has been working for more than 10 years on the development of resonators and filters exploiting the propagation of guided elastic waves in piezoelectric thin films. It has also proposed several concepts for frequency agile resonators and filters.
The purpose of this post-doc will be to further develop these ideas and to apply them to the design of demonstrators matching realistic specifications. In collaboration with the other member of the project team, more focused on fabrication in clean rooms, the candidate will propose innovative structures demonstrating frequency tuning of reconfigurability, and will take in charge their electrical characterization.
Wireless biological sensor using 2D materials (Graphene , Molybdenium disulfide)
The main goal of the post-doctoral position is the fabrication of a biological sensor using 2D materials and that can be remotely addressed thanks to a RF antenna simultaneously fabricated alongside the biosensor.
The post-doctoral associate will be in charge of the fabrication and characterization of the prototype. Starting from well-designed modelling, he/she will first establish a design architecture for the sensor and RF antenna. Once designed and sized, the post-doctoral associate will adapt existing transfer protocol of 2D materials to develop an innovative fabrication process for the sensor. He/she will then fabricate the first prototypes of the sensors. Consecutively he/she will validate first the remote addressing of the sensor via the RF antenna. Secondly he/she will lead biodétection tests to assess the sensitivity of the fabricated sensors. Finally, he/she will try to integrate Transition Metal Di-chalcogenides 2D materials (such as MoS2) to graphene sensors inside a hybrid 2D materials biological sensor. The goal here will be to boost operational sensitivity.
Conversational Agent for Medical Serious Games
The LVIC laboratory participates in a research project which aims to develop innovative tools for teaching medical students. The training will be done through serious games of second generation, in which the learner can interact directly with the environment:
- immersed in a 3D environment with a Virtual Reality Head Mounted Display and motion detection,
- with natural and ecological handling of the environment (instruments, patient …),
- and a voice interaction with conversational and emotional avatars.
The multimedia team of LVIC laboratory is involved in the project to develop tools allowing students to interact in natural language with conversational avatars.
In this context, the post-doctoral researcher will be in charge of:
- studying the state of art of conversational agents;
- understanding and mastering the technological components of the laboratory language processing;
- proposing and developing a dialogue system allowing interaction in natural language with conversational avatars of the project.
Application of ontology and knowledge engineering to complex system engineering
Model-Based System Engineering relies on using various formal descriptions of the system to make prediction, analysis, automation, simulation... However, these descriptions are mostly distributed across heterogeneous silos. The analysis and exploitation of the information are confined to their silos and thereby miss the big picture. The crosscutting insights remain hidden.
To overcome this problem, ontologies and knowledge engineering techniques provide desirable solutions that have been acknowledged by academic works. These techniques and paradigm notably help in giving access to a complete digital twin of the system thanks to their federation capabilities, in making sense to the information by embedding it with existing formal knowledge and in exploring and uncovering inconsistencies thanks to reasoning capabilities.
The objective of this work will be to propose an approach that gives access to a complete digital twin federated with knowledge engineering technologies. The opportunities and limits of the approach will be evaluated on industrial use cases.
Charge to spin conversion in HgTe topological insulators
The intrinsic spin-momentum locking of Dirac fermions at the surface or interface of topological insulators opens the path towards novel spintronic effects and applications.
Strained HgTe/CdTe is a model topological insulator and a very good candidate to design and demonstrate new spintronic devices exploiting the very large charge to spin conversion efficiency expected for such 2D systems. This postdoc position aims at realizing the first demonstration of the direct charge to spin conversion in topological HgTe nanostructures and use this demonstration as a building block for spin based logic elements.
New reference radiation field for radioprotection in the range of Cs-137 et Co-60 using an electrostatic electron accelerator
During the last years, LNHB has started and realized a research program in order to produce a reference photon radiation field for the radioprotection needs at high energies (~6 MeV) using its medical electron accelerator Saturne 43. For this purpose, a target and its appropriate flattering-attenuating filter have been designed by LNHB in order to produce the required photon field.
Nowadays there is no existing device able to produce radiation fields from an accelerator in the Cs-137 and Co-60 equivalent energy range. In order to achieve this, one needs the technology to construct and properly use absolute dosemeters for photons (cavity ionization chambers), to determine the right target-filter assembly allowing the production of the required photon field and to accurately calculate the conversion factors from air-kerma to operational quantity which is the dose-equivalent using the spectral distribution at the calibration position.
The candidate will participate in the construction of cavity ionization chambers needed for the characterization in terms of dose-equivalent of radiation field obtained from the electron accelerator and to the on-site measurements. He(She) will also be in charge with Monte-Carlo simulations in order to optimize the target-filter assembly used to produce the reference photon field from an electrostatic accelerator.
Software and hardware combined acceleration solution for operations research algorithms
The purpose of the study is to prepare the next generation of OR solvers. We will study the hardware acceleration possibility based on FPGA to run some or all of the OR algorithm. The blocks for which such a solution is not effective can be parallelized and executed on a standard computing platform. Thus, the proposed runtime correspond to a standard computing platform integrating FPGA. To access to this platform we require a set of tools. These tools should provide features such as (a) analysis and pre-compiling an input or problem or sub-problem of OR, (b) HW / SW partitioning and dedicated logic optimization and finally (c) generating an software executable and a bitstream.
The first step will be to find OR algorithms that are well suited for hardware acceleration. We then propose a HW / SW partitioning methodologies for different classes of algorithms.
The results will be implemented to lead to a compilation prototype starting from an OR instance and generating a software executable and a bitstream. Theses results will be implemented and executed on a computing platform integrating FPGA to evaluate the performance gain and the impact on the energy consumption of the proposed solution.