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Doctoral thesis viva voce: Séverine Rose

Vincent Montigny — 2013-06-12T14:22:14Z

Polymer-silica interactions: from structure to mechanical reinforcement of hybrid hydrogels

Séverine Rose, doctorante - PhD student Crédits : ESPCI ParisTechWe are investigating the consequences of the introduction of inorganic nanoparticles in a polymer hydrogel. The specific interactions existing between poly(N,N-dimethylacrylamide) and silica nanoparticles are at the origin of a strong mechanical reinforcement in terms of stiffness and strain at failure. Indeed, the impact of silica nanoparticles onto the general characteristics of hydrogels has been investigated in terms of structural, thermodynamical and mechanical properties. The study of the mechanical properties of hybrid hydrogels has been conducted in details with a special focus on PDMA/silica interactions at different strains and probing the time-scale effects. A strong time-dependence has been evidenced and a brief modelling of the hybrid structure has been proposed, taking into account the viscoelastic nature of the system. The behaviour of these hybrid hydrogels can be described as double networks. The PDMA/silica specific interaction has also been studied by light scattering experiments, evidencing several dynamics. We show that the general reinforcement can be controlled by the dynamics of the PDMA/silica association.

Contact :

Key words: hybrid hydrogels, silica nanoparticles, specific interactions, mechanical reinforcement, light scattering, neutron scattering.

Habilitation thesis viva voce: Cécile Monteux

Vincent Montigny — 2013-06-10T14:02:43Z

- 2013 / Soutenances de thèse

Doctoral thesis viva voce: Sandrine Le Tirilly

Vincent Montigny — 2013-06-06T12:52:24Z

Sandrine Le Tirilly, Doctorante - PhD Student Crédits : ESPCI ParisTech

Fragrance encapsulation: Specific interactions control at the oil-water interface

To comply with the industrial secret, this defense will be held in camera

BME Seminar: S. Marinesco (Centre de Recherches en Neurosciences de Lyon)

Vincent Montigny — 2013-05-17T08:15:58Z

Stéphane Marinesco, responsable de la plate-forme NeuroChem, Centre de Recherches en Neurosciences de Lyon (CRNL), Inserm U1028, CNRS UMR5292 et Université C. Bernard (Lyon I).

Abstract :

A large variety of biosensors is now used in biomedical settings to provide fast and simple measurements of physiological parameters at the bedside of patients or in laboratory animals. Among all biosensor devices that have been developed for medical applications, glucose biosensors are probably the best known to the public and represent a multi-billion dollar market. These biosensors can now be directly implanted in the human body, providing online continuous measurements and eliminating the need for drawing blood samples. I will briefly review the state of the art for such implantable glucose biosensors. I will then focus on biosensor devices that can be implanted in the brain of laboratory animals. Such devices are based on microelectrodes that minimize tissue lesions and use natural enzymes for biological recognition. Such microelectrode biosensors are currently used for detecting neurotransmitters and metabolites, and decipher the mechanisms of chemical communication in the brain. I will review the structure of the brain parenchyma with the intracellular, extracellular and vascular compartments. I will then discuss the specific problems related to the implantation of a probe into the brain, also known as the foreign body response, and the overall interest of invasive measurements compared to non-invasive methods such as optical microscopy or magnetic resonance imaging. I will finish by an overview of the engineering and fabrication of microelectrode biosensors and by a discussion of recent results obtained in our laboratory regarding their specificity for neurotransmitter detection.

Doctoral thesis viva voce: Clémence Vergne

Vincent Montigny — 2013-05-15T09:14:53Z

Study of biomimetic objects and polymer valves in microfluidics

Clémence Vergne, doctorante - PhD student Crédits: ESPCI ParisTechThe first part of my thesis is dedicated to the study of the mechanical properties of neutrophils. It concerns a pathology, the Acute Respiratory Distress Syndrome (ARDS), characterized by an increase of the elastic modulus of neutrophils, that leads to a massive trapping of them in lung blood capillaries. We have chosen to study two types of model objects.
First the THP1, an immortal cell line commonly used as a model of neutrophils, and then microgels beads that are chemically crosslinked using droplets as microreactors. We have investigated the properties of that objects, by stressing them into microchannels under different flow conditions and with different confinements. In another part I worked on a novel technology allowing the integration of microvalves and micropumps in lab-on-a-chips made of either soft or hard materials. The approach is based on the grafting of responsive hydrogels onto the microchannel walls.
These gels undergo large volume variations by absorbing or expelling water when subjected to external stimuli. The hydrogel thin films we studied here are chemical polymer networks that are covalently bound to the surface. The first step of the elaboration of theses valves is the development of the surface-attached hydrogel thin films. The objective is to obtain hydrogel films with a wide range of thicknesses. The second step is the completion of the microfluidic system by bonding a channel on the active surface and the application of different types of stimuli.

Habilitation thesis viva voce: Emmanuel Geron

Vincent Montigny — 2013-05-13T15:34:43Z

Contributions to telecommunications and instrumentation

Emmanuel Géron Crédits : ESPCI ParisTechManufacturers of telecommunications systems are constantly looking for improvements in their systems and especially in microwave modules. Development of circuits in hybrid technology combined with the control of all interactions between the different functional subsystems can improve consumption or manufacturing reproducibility. Thorough knowledge of complex telecommunication standards allows in many cases to introduce additional electronic circuits in order to provide interesting innovations for example to the data flow, or to the time needed to establish connections. This is the case for multiple access point and adaptive antennas. The latter by the optimization of their radiation pattern allows optimization of the coverage areas and reduction of the radiated power which is a public health issue. Metamaterials, in their one-dimensional form, are also a way to improve or develop new functional microwave circuits such as microwave coupler with a variable coupling rate. Systems and techniques developed in the context of telecommunications can be adapted to resolve issues related to instrumentation. Instrumental or theoretical knowledge is highly transferable to realise physical measurements. This is the case for measuring moisture in wood chips or positioning a vehicle on the road. Techniques used for microwave telecommunications can also be adapted to overcome the resolution limit of the space charge measurement in insulating materials.

Doctoral thesis viva voce: Aurélien Duboin

Vincent Montigny — 2013-05-03T10:13:56Z

Complex fluid flows and interface dynamics in microfluidic systems

Aurélien Duboin, doctorant - PhD student Crédits : ESPCI ParisTechTo better understand enhanced oil recovery processes, we performed immiscible biphasic flows in microfluidic geometries, involving oil phases and aqueous phases. We study the effect of the addition of polymers in the aqueous phase on the water/oil interface dynamics.
We work first in a common microfluidic flow-focusing geometry, implying elongational flows, with a semi dilute polymer solution as the outer phase and a Newtonian oil as the inner phase. We observe new interface regimes linked to the non-Newtonian behavior of the outer phase. The elongational properties of the polymer solution favour the formation of cusps and micrometric jets, and the normal stresses that arise in the polymer solution, contribute to stabilize the jet over large distances which allow us to produce microfibers in the system. _Besides, we use geometries simulating the typical configuration of a reservoir in oil industry, so as to study, in a systematic way, the effects of polymer solutions (viscosity/elasticity) on the oil phase driving, at pore and network scales. We characterize the influence of the viscosity ratio, the capillary number and wetting conditions, on the global pattern in the network and on the oil recovery rate.
Lastly, we implement a dry-phase surface treatment method to improve the hydrophilicity of a material compatible with crude oil flows, and succeed in making microsystems with controlled and patterned wettability, down to the micrometric scale.

Aurélien Duboin PhD student at the MMN laboratory

Ultrafast imaging and cardiovascular diseases: the CNP Assurances Foundation supports a new research project

Vincent Montigny — 2013-04-26T08:41:00Z


Mickaël Tanter, directeur de recherche INSERM à l'Institut Langevin de l'ESPCI ParisTech

The CNP Assurances Foundation is giving its support to the École Supérieure of Industrial Physics and Chemistry of the City of Paris (ESPCI ParisTech) in its ambitious research project directed by Mickael Tanter (photo), intended to improve the detection and management of heart contraction abnormalities. These dysfunctions affect one million individuals in France and are responsible for numerous deaths.

Such abnormalities are difficult to detect

Cardiovascular diseases constitute the main cause of mortality worldwide, ahead of infectious diseases and cancer. Some of these deaths are due to cardiac insufficiencies, often consecutive to contraction abnormalities of the heart. These dysfunctions, such as cardiac arrhythmia and ventricular desynchronisation, currently affect close to one million individuals in France. The ageing of the population only exacerbates the problem.
With conventional examination techniques, such as electrocardiograms or MRI, electrical abnormalities of the heart, which lead in time to cardiac insufficiency, cannot yet be detected early on and located with sufficient precision.

An ultrafast ultrasound imaging technique

The Inserm U 979 research team “Physics of Waves for Medicine” of the Institut Langevin of ESPCI (École Supérieure of Industrial Physics and Chemistry of the City of Paris) has developed an ultrafast ultrasound imaging technique (12,000 images/second), which in time will be usable to visualise and measure the electromechanical activation of the heart at a very fast rate.

Contact :

Capable of achieving rates of thousands of images per second, this new non-invasive technique allows the propagation of mechanical vibrations inside organs to be observed in real time with millimetre precision, the velocity of these waves being associated with the local hardness, making it possible to obtain a quantitative map of the hardness of tissues. In the case in point, ultrafast imaging of the heart will allow early detection of dysfunctions connected with electrical conductivity, and to differentiate very early between benign conditions and serious conditions requiring a major operation, such as the fitting of a pacemaker.

Challenges to overcome

It will be a case of applying this ultrafast imaging technique, which has proven itself in the detection of certain tumours, such as those of the breast, to observation of the contraction movements of the heart. However, adapting this ultrafast imaging technique to measurement of the rigidity of the myocardium, as well as to high-resolution visualisation of the electrical activity of the heart, raises new difficulties, but we believe we can solve them. Our goal is full validation of these new imaging approaches in patients within two or three years,” explain Mickaël Tanter, director of research at the Institut Langevin in ESPCI ParisTech, and Mathieu Pernot, head of Inserm research.
Financed by ESPCI, Inserm and the CNP Assurances Foundation, this project will lead to the creation of an ultrafast 3D image prototype for cardiovascular research, scheduled for 2015. It is planned to allow a resolution of 5000 images per second simultaneously in multiple regions of the heart, compared with 50 images per second for the echocardiography systems currently in clinical use.
The project is being conducted in association with the team of Prof. Haissaguerre (Haut-Lévêque Hospital, Bordeaux), international expert in the field of cardiac arrhythmia. The team, directed by Mickaël Tanter at the Institut Langevin, is made up of 13 permanent researchers (CNRS, ESPCI and Inserm), 8 postdoctorals, one of whom was recently recruited to bring forward the rapid heart imaging project, and 20 doctoral students.

The site of the Institut Langevin de l'ESPCI ParisTech
The site of the Fondation CNP Assurances

This project is supported by the ESPCI Georges Charpak Endowment Fund

Mathias Fink joins the "Commission Innovation 2030"

Vincent Montigny — 2013-04-20T09:17:00Z

Mathias Fink, ESPCI Professor and Director of the Institut Langevin of ESPCI ParisTech was nominated to the 2030 Innovation Commission, presided by Anne Lauvergeon and inaugurated by the President of the Republic on 19 April.

The mission of the 2030 Innovation Commission is to identify “the sectors and technologies in which France is capable of commanding leading positions by 2030, while promoting the activities which […] will create the greatest value and the most employment”.

An innovation competition will be set up for each industrial challenge adopted. It will be open to all enterprises, start-ups, medium-sized enterprises (MSEs), large groups and foreign enterprises who wish to invest in France.

€150 million will be allocated, in addition to the use of private finance.

Contact

To find out more :

> The communiqué de presse of the Elysée.

> The photos of the installation of the committee on 19 April by François Hollande, attended by Jean-Marc Ayrault, Arnaud Montebourg, Geneviève Fioraso and Fleur Pellerin.

ESPCI and Nexans sign a scientific partnership agreement

Vincent Montigny — 2013-04-04T08:58:00Z

On March 20 at the Hôtel de Ville in Paris, the École Supérieure of Industrial Physics and Chemistry of the City of Paris, the company Nexans and the ESPCI Georges Charpak Endowment Fund signed an agreement to create a partnership promoting excellence in research. At the heart of the project lies the science and technology of the transport of energy.

Signed by Jean-Louis Missika, President of ESPCI ParisTech and deputy to the Mayor of Paris responsible for innovation, research and universities, Frédéric Vincent, President and Director General of Nexans, and Jacques Lewiner, President of the ESPCI Georges Charpak Endowment Fund, this agreement establishes cooperation in science and innovation between Nexans, world leader in the field of advanced cables, and ESPCI ParisTech, ranked as the foremost French engineering school by the Shanghai Classification.
Jean-Louis Missika was pleased to welcome the move by Nexans as “a pioneering enterprise among the partners of ESPCI ParisTech, a school whose research can provide a crucial competitive advantage for the company”.
Frédéric Vincent indicated that “Nexans needed to develop technical expertise; this agreement is the best way of achieving that in the field of nanotechnology, polymers and high voltage”.

About Nexans
With energy at the basis of its development, Nexans, worldwide expert in the cable industry, offers an extensive range of cables and cabling solutions. The Group is a global player in the energy transmission and distribution, industry and building markets. Nexans addresses a wide series of market segments: from energy and telecom networks to energy resources (wind turbines, photovoltaic, oil and gas, and mining) to transportation (shipbuilding, aerospace, automotive and automation, and railways). Nexans holds an unique expertise in the field of superconducting cables.

An ambitious scientific project

There are a number of research fields at the heart of the joint venture. These include, under the leadership of Stéphane Holé, electrical insulation and more particularly the study of insulators and their interfaces for high-voltage devices, and methods of characterizing insulating material by measuring the space charge distribution. Other areas are: superconductor materials and new polymer materials

Three presentations gave a foretaste of the variety of innovative research carried out by ESPCI ParisTech:

• the vitrimer, a material developed by Ludwik Leibler, associate professor at ESPCI ParisTech, director of the Laboratory for Soft Matter and Chemistry (MMC) and recipient of the CNRS Medal for Innovation in 2013;

• ultrafast medical imaging, developed by Mickaël Tanter, director of research at the Institut Langevin of ESPCI ParisTech;

• superconductivity and Meissner effect levitation, studied by Jérôme Lesueur, professor and director of the Laboratory of Physics and Materials Study (LPEM).

During the ceremony, the engineering students Aurélien Baelde and Kejian Wang gave a demonstration of superconductivity using a levitating train made by them at the Langevinium, the School's HackLab, of which they are the cofounders with their colleague Guillaume Chatté. There remarkable demonstration captured the attention of the public and greatly contributed to the success of the day.