27 novembre 2015

  • Séminaire de Racha Gana : Study and development of a multimodal micromechanical/optical device for the maturity characterization of human oocytes

Résumé : During artificial fertilization attempt using intracytoplasmic injection (ICSI) or in vitro fertilization (IVF), clinicians have to select mature oocytes in order to maximize pregnancy opportunity. This qualification is based on visual estimation of the morphology of oocytes under microscope. Unfortunately, the results obtained by this method are not accurate enough. The ultimate aim of our work is to develop a device able to qualify oocytes with more precision and to determine the perfect moment for successful fertilization using different modality of characterization (mechanical, optical and morphological). In this presentation, the new force sensor developped for the mechanical characterization of human oocytes will be presented. This sensor uses passive magnetig springs. Contrary to the magnetic force sensors previously developed that are using diamagnetic levitation or upthrust buoyancy to passively stabilize the magnetic springs, a mechanical repulsion effect is here used to achieve this stabilization. This specific implementation makes the sensor compatible with the recommandations imposed by the Biomedecine Agency in the context of the Medically Assisted Procreation (MAP). Some mechanical modelings of human oocytes behaviour will be also presented in order to extract possible significant parameters for futur diagnosis of oocyte maturity.

26 novembre 2015

  • Présentation de Emmanuel Piat : Mesures de micro et nanoforces par ressorts magnétiques passifs couplés à des faibles masses : exemples et applications

Cette présentation a été faite à la journée thématique "Métrologie des très faibles forces : quelle traçabilité sous le milligramme et le micronewton - quel impact sur les nanotechnologies ?" du GT2 du club nanoMétrologie (LNE - Paris, 26 nov. 2015).

Contexte de la présentation : Les capteurs de micro et nanoforce utilisant des ressorts magnétiques passifs associés à des masses rigides macroscopiques de quelques milligrammes à quelques grammes sont des capteurs basse fréquence qui peuvent constituer une alternative possible aux capteurs de force utilisant des microstructures élastiques lorsque les forces à mesurer ont une dynamique limitée à quelques Hertz. Cette présentation développera le concept de ressort magnétique passif et le déclinera à travers plusieurs réalisations développées à l'institut femto-st pour caractériser des matériaux fonctionnalisés ou des cellules biologiques. Les forces et les faiblesses de ce type de capteur seront explicités et les enjeux associés aux travaux en cours seront développés dans le contexte de la métrologie des faibles forces.

15 octobre 2015

  • Séminaire de Andrey Kudryavtsev : Autocalibration of SEM for 3D imaging

Résumé : The first and one of the crucial steps of 3D reconstruction is the calibration of the vision system. In most cases a calibration pattern is used. It represents an object with known dimensions and textures. In the case of 3D reconstruction using a Scanning Electron Microscope, the use of such object with knwown geometry is problematic because the manufacturing of high quality nano-sized objects is complicated. Currently, the inaccuracies in the object dimensions will highly influence the quality of the calibration. The advantage of the auto-calibration consists in the fact that it allows to calibrate a vision system using the same images as for 3D reconstruction and avoid the use of a calibration pattern. In this work, SEM is modeled as an affine camera (camera with a parallel projection). We will formulate the problem for such type of camera, define a minimization criteria and solve the camera parameters research with an adapted algorithm.

  • Information diverses
  • Bilan vidéos SPECIMeN fournies pour la vidéo AS2M des JJCR/JNRR
  • Points sur les projets ANR en cours de montage

15 septembre 2015 : réunion de rentrée SPECIMeN

  • Séminaire de Margot Billot : External mechanical disturbances compensation with a passive differential measurement principle in nanoforce sensing using diamagnetic levitation

Résumé : Nanoforce sensors using passive magnetic springs associated to a macroscopic seismic mass are known to be a possible alternative to force sensors based on elastic microstructures like Atomic Force Microscopes if the nanoforces that have to be measured are characterized by a bandwidth limited to a few Hertz. The estimation of the unknown force applied to the seismic mass is based on the deconvolution of the noisy measurement of the mass displacement which has an under-damped dynamic. Despite their high performances in terms of linearity, resolution and measurement range, such force sensors are extremely sensitive to low frequency environmental mechanical disturbances, like the angular variations of the anti-vibration table supporting the device or the residual seismic vibrations that are not filtered by the table. They are also sensitive to the temperature evolution of the ambient air. The evaluation, modeling and compensation of such environmental disturbances have to be specifically studied in the context of magnetic springs associated to a macroscopic seismic mass because of their important negative effects in terms of low frequency drifts and oscillatory disturbances. This article presents an estimation and a passive compensation strategy of the low frequency and non-stationary mechanical disturbances that is based on a differential principle. This approach is applied to a nanoforce sensor based on diamagnetic levitation developed in the last decade. It does not necessitate to add new types of sensors in the measurement chain such as very high resolution and low frequency inclinometers or accelerometers in order to estimate the mechanical disturbances. In term of performances, the force estimation error remains in the nanonewton level over periods of time of several minutes when external temperature remains constant.

  • Nouvel entrant
  • Information rentrée
  • journées JJCR/JNRR
  • Bilan projets à monter pour les AAP 2016
  • Projection film promotionnel Biom-@x (contient la caractérisation ovocytaire)
  • Prochains séminaires SPECIMeN