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

PhD : selection by topics

Fast Transcranial Acoustic Simulations and adaptive imaging for Personalized Dosimetry in Ultrasound Brain Therapy

Département Imagerie Simulation pour le Contrôle (LIST)

Laboratoire Simulation et Modélisation en Acoustique

01-10-2020

SL-DRT-20-0700

sylvain.chatillon@cea.fr

Health and environment technologies, medical devices (.pdf)

The treatment of brain diseases remains very difficult, mainly because of the poor access of pharmacological agents to the brain due to the presence of the blood-brain barrier (BBB). Focusing low intensity ultrasound waves in the brain, combined with circulating microbubbles (ultrasound contrast agents), significantly increases the release of the drug into brain tissue, with an established therapeutic effect in many animal models. This permeabilization of the BBB is non-invasive, local and reversible provided that the intensity of the beam is well controlled through the skull because the implosion of microbubbles could lead to microhemorrhages. The structure and the complex geometry of the skull bone lead to a strong attenuation as well as specific phase shifts of the ultrasonic wave front during its crossing. The features of the focal task are severely impaired and the use of personalized simulation is unavoidable to ensure reproducible, controlled and safe therapy. These aberrations can be corrected by using a phased array ultrasonic probe of large aperture associated with delay laws calculated notably from ultrasonic wave propagation models, using a description of the morphology of the skull obtained by MRI or computed tomography (CT). In addition, the relative instability of the microbubbles makes it necessary to monitor their cavitation activity in order to be able to intervene in real time in the event of an acoustic signature announcing a risk of definitive lesion of the tissues (ultra-harmonic and broadband cavitation). Thus, in the previous NeuroSpin work, the use of a feedback loop based on passive cavitation detectors makes it possible to guarantee the safety of the macaque protocol. To go beyond the simple detection of these signals, it would be desirable to be able to map this activity through the skull using passive imaging with correction of aberration on reception. The objective of this hesis is to adapt and optimize the numerical simulation and imaging tools developed by CEA-LIST for Non Destructuve Testing (NDT) applications in order to: (i) predict and correct the pressure field obtained during a Transcranial Focused Ultrasound Therapy and (ii) significantly improve the quality of passive acoustic cavitation mapping during the procedure. This thesis, carried out in collaboration between the S. Chatillon team at the DRT / LIST and that of B. Larrat at the DRF / JOLIOT / NeuroSpin, will comprise the following three stages: - Validation of the propagation model on samples of human skulls. - Optimization of the trajectory to reach a target point to be treated (inverse problem). - Transcranial imaging of microbubble cavitation activity during the procedure

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Fine chemical nanocaractisation of GaN structures for nano and opto-electronic applications

Département des Plateformes Technologiques (LETI)

Autre laboratoire

01-10-2020

SL-DRT-20-0701

marc.veillerot@cea.fr

Advanced nano characterization (.pdf)

The use of III-N materials is widespread, not only for the electronic power components but also for new low consumption lighting technologies based on µLEDs. However, a better control of the material properties (composition & doping) as well as the quality of critical interfaces is necessary to increase the electrical performance of the components. XPS and SIMS chemical characterization techniques are already being used to help improving these structures. However, both of these techniques need to be developed and combined to produce the reliable information needed to optimize materials and fabrication processes for GaN-based devices. This PhD subject is built on two lines of work. The first, of immediate industrial interest, is the fine combined characterization of surfaces and interfaces for thin planar stacks (a few nm) of AlGaN / GaN and oxide / GaN type. The development of specific methodologies is required such as low energy SIMS for high depth resolution and high energy XPS for analysing buried interfaces. The second, more prospective, is the characterization of three-dimensional structures integrated into the final devices of micron size. For this purpose, we will focus on variants of XPS and SIMS techniques with higher lateral resolution. This part of the work, carried out in collaboration with academic and / or industrial partners, will make it possible to anticipate the characterization capabilities of future devices.

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Innovative package using ultra-thin chip transfer on substrate (UTCoS)

Département Composants Silicium (LETI)

Laboratoire Packaging et 3D

01-07-2020

SL-DRT-20-0703

gabriel.pares@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

The subject is in the field of advanced microsystems, which is a strategic axis for CEA-LETI associated with current packaging trends: extreme compactness, conformability and functionalization. The approach developed is unique and allows the carrying of ultra-fine chips ("substrate-less ") on any type of host substrates with a process adaptable to different bonding solutions including direct bonding or with an intermediate layer. It uses CEA-leti's expertise in ultra-thinning of layers, temporary and permanent bonding techniques, thin layer transfer on temporary carrier and advanced cutting techniques (plasma, laser). In addition, it uses advanced packaging technologies with thin FLEX substrates, molding encapsulation and additive technology interconnections (RDL, 3D printing and screen-printing). The proposed solution is generic and addresses many applications as CMOS image sensors, MEMS (sensors and piezo-electrics actuators), RF ICs (filters, switches, antenna arrays). The focus of the study will be on CMOS image sensor with passive and active focal plan curvature with the objective of realizing a first functional demonstrator.

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Colorimetric detection of organophosphorus based pesticides: From organic synthesis to colorimetric paper detector

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire Synthèse et Intégration des Nanomatériaux

01-09-2020

SL-DRT-20-0714

sebastien.penlou@cea.fr

Health and environment technologies, medical devices (.pdf)

This PhD thesis deals with the design and synthesis of chromogenic dyes and the processing method needed for the development of chromogenic detector of organophosphorus pesticides. A chromogenic dye is a molecule that changes color when it is in the presence of a target molecule. At the CEA Grenoble, the LSIN laboratory has developed an expertise around the colorimetric detection, via the screening of a chemical library of commercial chromogenic dyes. We identified commercial reactive structures. The aim of this thesis is to synthesize more reactive structural analogues with controlled color change. It is proposed to validate the actual color changes on organophosphorus pesticides. Finally, the study of the reactivity of chromogenic dyes versus organophosphorus pesticides (NMR, FTIR, UV-vis-NIR, mass spectrometry, ...) should allow us to better understand their reactivity and propose a reaction mechanism explaining the color changes observed. A prototype of a low-cost organophosphorus pesticide colorimetric detector will be developed at the end of the thesis.

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Surface physico-chemical properties modification by multi-scale nano-patterning

Département des Plateformes Technologiques (LETI)

Laboratoire

01-10-2020

SL-DRT-20-0720

maxime.argoud@lcea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Over the past 20 years, surface patterning methods have been developed in the field of advanced lithography for microelectronics. These breakthrough techniques, such as directed self-assembly of block copolymers or nano-imprint lithography, appeared to be a credible low-cost alternative to traditional optical lithography methods. Many studies have demonstrated and confirmed this potential, up to the 300mm wafer scale, however these technologies have not been tranferred for CMOS applications, particularly because of the defectivity and the industrialization of the extreme UV lithography. The maturity of the various processes and materials developed, as well as the associated global understanding, now offers many opportunities for applications for which defectivity is not critical. In particular, the modification of the surface physico-chemical properties by nano-patterning, on several scales, using of the relatively low-cost patterning techniques previously mentioned, could address many application domains (optical properties, biotechnologies, self-assembly of chips ...). The thesis work will focus on the modification of surface physico-chemical properties by nano-patterning. The surface patterning will be achieved by advanced patterning technologies such as self-assembly of block copolymers, over a wide range of periods (from 20 to 200nm), directed or not, and also by nano-imprint lithography. A working axis will concern the implementation, and the associated understanding, of these patterning techniques. Various thin layers or bulk materials may be structured, and the physico-chemical properties obtained will be finely characterized. An original axis of the work will also focus on the multi-scale aspect of this pattering, from the point of view of patterning itself over a wide range of dimensions (from a few nm to several hundred nm), or from the dimension of the modified surfaces (from a few hundred nm² to several tens of cm²). Some properties can be applied to various application domains (optics, biotechnologies, chip self-assembly ...).

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Innovative haptic interface

Département Composants Silicium (LETI)

Labo Composants Micro-actuateurs

01-09-2020

SL-DRT-20-0724

fabrice.casset@cea.fr

Cyber physical systems - sensors and actuators (.pdf)

A haptic interface allows to the user to interact with its environment by the sense of touch. It can be used for example to give complex information in harsh, noisy or low visibility environment. Today, demonstrators provide haptic effects essentially on glass screen. We propose to develop innovative haptic solutions to generate complex effects on curved surfaces, conformable, and potentially in various materials such as metal, plastic? The objective of the candidate will be to design, build and characterize haptic interfaces. A reflection will be conducted on the different possibilities to integrate this haptic function on various substrates. To do this, he will develop analytical models and use finite element method (COMSOL). Supervised by CEA experts on the subject, he will propose the most adapted technology (thin-film actuators or bulk piezoceramics) to integrate piezoelectric actuators able to generate the haptic effect on curved surfaces, conformable, ideally flexible. Finally, a reflection on the global system will be necessary in order to propose an innovative and complex haptic demonstrator integrating different functions such as finger position detection, actuation and driving mechanisms.

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