Papers by Olivier Français
Sensors and Actuators B: Chemical, 2015
ABSTRACT Current methods for the In vitro diagnostics of bloodstream infections are based on bloo... more ABSTRACT Current methods for the In vitro diagnostics of bloodstream infections are based on blood culture, followed by phenotypic characterization of the pathogen. Such methods have shown their advantages in term of sensitivity (down to 1 bacterium in 10 mL whole blood) and robustness, but require 3 to 4 days, which is too long in the case like sepsis, where a fast and appropriate medical treatment is needed. There is thus a very strong interest in blood sample decomplexi�cation methods to be coupled to the existing analytical means (optics, molecular ampli�cation). In this paper, we report the continuous ow capture and concentration of microorganisms spiked in a blood sample, owing within a dedicated micro uidic device. The separation is achieved with dielectrophoresis (DEP) forces, using hypotonic conditions for the bu�er. We demonstrate e�cient and real-time accumulation of target pathogens from blood in our micro uidic device, thus providing a decomplexi�ed sample suitable for further characterization. In particular, up to 97 % capture rate could be observed with E. coli micro-organisms. Simultaneous separation of di�erent micro-organisms (Gram+, Gram- and yeast) could also be achieved, showing the versatility of the method and device.
Computer Methods in Biomechanics and Biomedical Engineering, 2015
Springer Proceedings Physics, 2007
J3eA, 2013
ABSTRACT Cet article présente l'utilisation d'un tissu biologique végétal, une po... more ABSTRACT Cet article présente l'utilisation d'un tissu biologique végétal, une pomme de terre, comme support pédagogique auprès d'élèves dans une formation EEA de niveau L3 pour les initier à la biologie et plus spécifiquement l'électro-physiologie. Il permet de sensibiliser les élèves au rôle que peut avoir l'E.E.A. dans des disciplines scientifiques très variées, et ici en particulier dans le domaine de la biologie. La partie expérimentale de cet enseignement, inclue une phase d'instrumentation pour la mesure, puis d'extraction des paramètres pour la détermination d'un modèle et enfin une phase d'étude d'effets induits par un choc électrique sur le tissu. En s'appuyant sur la mesure d'une bio-impédance dans la gamme [100Hz – 5MHz] les élèves établissent le modèle équivalent électrique du tissu biologique mesuré, ici un morceau de pomme de terre. Ils mettent en évidence le comportement en fréquence du tissu biologique et sa nature: assemblage de cellules au sein d'un milieu extracellulaire conducteur (conduction ionique). Deux modèles électriques sont confrontés aux mesures expérimentales (modèle de Fricke et de Cole-Cole) par une extraction des paramètres en utilisant la méthode des moindres carrés et comparés pour en voir les limites. Enfin, une fois les modèles assimilés, les élèves étudient l'évolution de la valeur des paramètres trouvés lors de l'application d'un choc électrique sur le tissu biologique et tente d'analyser ce qui se passe au sein du tissu. Au final, les élèves de L3 y ont vu un regard qu'ils n'imaginaient pas de l'EEA, très appliqué et original à l'aide d'un support étonnant que constitue une pomme de terre.
Computer methods in biomechanics and biomedical engineering, 2012
Biomicrofluidics, 2013
Cell fusion consists of inducing the formation of a hybridoma cell containing the genetic propert... more Cell fusion consists of inducing the formation of a hybridoma cell containing the genetic properties of the progenitor cells. Such an operation is usually performed chemically or electrically. The latter method, named electrofusion, is considered as having a strong potential, due to its efficiency and non-toxicity, but deserves further investigations prior to being applicable for key applications like antibody production and cancer immunotherapy. Indeed, to envision such applications, a high amount of hybrid cells is needed. In this context, we present in this paper a device for massive cell pairing and electrofusion, using a microarray of non-connected conductive pads. The electrofusion chamber--or channel--exposes cells to an inhomogeneous electric field, caused by the pads array, enabling the trapping and pairing of cells with dielectrophoresis (DEP) forces prior to electrofusion. Compared to a mechanical trapping, such electric trapping is fully reversible (on/off handling). The DEP force is contactless and thus eases the release of the produced hybridoma. Moreover, the absence of wire connections on the pads permits the high density trapping and electrofusion of cells. In this paper, the electric field mapping, the effect of metallic pads thickness, and the transmembrane potential of cells are studied based on a numerical model to optimize the device. Electric calculations and experiments were conducted to evaluate the trapping force. The structure was finally validated for cell pairing and electrofusion of arrays of cells. We believe that our approach of fully electric trapping with a simple structure is a promising method for massive production of electrofused hybridoma.
Volume 2: Automotive Systems, Bioengineering and Biomedical Technology, Fluids Engineering, Maintenance Engineering and Non-Destructive Evaluation, and Nanotechnology, 2006
ABSTRACT The present work is an experimental study of shear horizontal surface acoustic wave (SH-... more ABSTRACT The present work is an experimental study of shear horizontal surface acoustic wave (SH-SAW) miniaturized sensors which offer a high potential for electrochemical applications in liquid environments and in real-time. Our devices consist of a 42° rotYX lithium tantalate (LiTaO3 ) substrate coated with an SU8 photoresist polymer in order to produce acoustic waveguides supporting a Love–wave. The sensors architecture and fabrication techniques are presented. Standard techniques employing continuous wave system and pulse mode measurements have shown the propagation of both surface skimming bulk waves (SSBW) and leaky SH-SAW (LSAW) on 42°rot YXLiTaO3 . A numerical calculation using a simple balanced summation waves model is presented. Taking into account waves reflections and our measured velocity values, the simulation is in accordance with measurement. A copper’s electrodeposition experiment was performed to estimate the sensitivity of SAW devices. The measured sensitivity of 0.38 cm2 .g−1 is discussed in the framework of previously published works concerning Love wave devices.
Procedia Engineering, 2010
CANEUS2006: MNT for Aerospace Applications, 2006
ABSTRACT Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Associat... more ABSTRACT Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
Antimicrobial Agents and Chemotherapy, 2015
Plasmodium falciparum is transmitted from humans to Anopheles mosquito vectors via the sexual ery... more Plasmodium falciparum is transmitted from humans to Anopheles mosquito vectors via the sexual erythrocytic forms termed gametocytes. Erythrocyte filtration through microsphere layers (microsphiltration) had shown that circulating gametocytes are deformable. Compounds reducing gametocyte deformability would induce their splenic clearance, thus removing them from the blood circulation and blocking malaria transmission. The hand-made, single-sample prototype for microsphiltration was miniaturized to a 96-well microtiter plate format, and gametocyte retention in the microsphere filters was quantified by high-content imaging. The stiffening activity of 40 pharmacological compounds was assessed in microtiter plates, using a small molecule (calyculin) as a positive control. The stiffening activity of calyculin was assessed in spleen-mimetic microfluidic chips and in macrophage-depleted mice. Marked mechanical retention (80% to 90%) of mature gametocytes was obtained in microplates following exposure to calyculin at concentrations with no effect on parasite viability. Of the 40 compounds tested, including 20 antimalarials, only 5 endoperoxides significantly increased gametocyte retention (1.5- to 2.5-fold; 24 h of exposure at 1 μM). Mature gametocytes exposed to calyculin accumulated in microfluidic chips and were cleared from the circulation of macrophage-depleted mice as rapidly as heat-stiffened erythrocytes, thus confirming results obtained using the microsphiltration assay. An automated miniaturized approach to select compounds for their gametocyte-stiffening effect has been established. Stiffening induces gametocyte clearance both in vitro and in vivo. Based on physiologically validated tools, this screening cascade can identify novel compounds and uncover new targets to block malaria transmission. Innovative applications in hematology are also envisioned.
Innovative Food Science & Emerging Technologies, 2015
Sensors and Actuators B: Chemical, 2015
ABSTRACT Current methods for the In vitro diagnostics of bloodstream infections are based on bloo... more ABSTRACT Current methods for the In vitro diagnostics of bloodstream infections are based on blood culture, followed by phenotypic characterization of the pathogen. Such methods have shown their advantages in term of sensitivity (down to 1 bacterium in 10 mL whole blood) and robustness, but require 3 to 4 days, which is too long in the case like sepsis, where a fast and appropriate medical treatment is needed. There is thus a very strong interest in blood sample decomplexi�cation methods to be coupled to the existing analytical means (optics, molecular ampli�cation). In this paper, we report the continuous ow capture and concentration of microorganisms spiked in a blood sample, owing within a dedicated micro uidic device. The separation is achieved with dielectrophoresis (DEP) forces, using hypotonic conditions for the bu�er. We demonstrate e�cient and real-time accumulation of target pathogens from blood in our micro uidic device, thus providing a decomplexi�ed sample suitable for further characterization. In particular, up to 97 % capture rate could be observed with E. coli micro-organisms. Simultaneous separation of di�erent micro-organisms (Gram+, Gram- and yeast) could also be achieved, showing the versatility of the method and device.
J3eA, 2015
A l'ENS de Cachan, le département E.E.A. a mis en place une série de travaux pratiques portant su... more A l'ENS de Cachan, le département E.E.A. a mis en place une série de travaux pratiques portant sur l'utilisation d'un microsystème « électro-fluidique », réalisé en salle blanche, pour le micro-positionnement par champ électrique d'objets inertes ou biologiques de dimension micrométrique. Cet enseignement est développé dans des formations de niveau Master.
Electrophoresis, Jan 29, 2015
The electric field is commonly used in microdevices to handle, treat or monitor living cells for ... more The electric field is commonly used in microdevices to handle, treat or monitor living cells for various biological or biomedical applications (cells electrofusion, gene electrotransfer, drugs injection, cell sorting, …). Dielectrophoresis (DEP) forces, using stationary waves (conventional DEP) or travelling waves, are widely used for the cell handling or sorting. Electrorotation, which is induced by a rotating electrical field, is used for the determination of cell dielectric parameters. The application of pulsed electric field (PEF) results in the cell membrane permeabilization that might allow the transfer of various molecules in the cytoplasm. In this paper we propose a method to monitor in-situ the level of electropermeabilization induced by PEF application on a single cell, by combining the dielectrophoresis force and the electrorotation torque within a microfluidic device. The method was experimented on two different cell lines (human leukemic T cell lymphoblast and murine me...
TRANSDUCERS 2007 - 2007 International Solid-State Sensors, Actuators and Microsystems Conference, 2007
Abstract The early developments of an optical gas sensor combining plasma ignition by silicon ele... more Abstract The early developments of an optical gas sensor combining plasma ignition by silicon electrode arrays and optical detection coupled with image processing are presented in this paper. The principle of the sensor under development is based on the ionization of ...
La Houille Blanche, 2003
ABSTRACT This paper is focused on experimental, numerical and analytical study of microfluidic de... more ABSTRACT This paper is focused on experimental, numerical and analytical study of microfluidic devices. These devices are obtained by DRIE Technique on a silicon wafer. We focused the study on microdiodes such as nozzle diffuser and Tesla diode. The microdiodes are then used in an electrostatic micropwnp. The first part describes the process and characterisation principle of the devices. All parameters of the structures are also described in order to obtain an optimum efficiency. In the second part, all the results are applied on the modelisation of the micropwnp. A simulator has been developed under Matlab with an hybrid description using both classical flow laws and electrical analogy.
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Papers by Olivier Français