Université PSL

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RECHERCHER

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Emulsification with rectangular tubes
Laboratoire Colloïdes et Matériaux Divisés - Erwan Crestel, Ladislav Derzsi, Hugo Bartolomei, Jérôme Bibette, and Nicolas Bremond*
Phys. Rev. Fluids - 4 073602 - DOI: 10.1103/PhysRevFluids.4.073602 - 2019
The flow of two immiscible liquids or fluids in bounded systems where confinement
geometry varies can lead to drop or bubble formation. This phenomenon has been reported
in the context of oil recovery and named snap-off, or exploited for making emulsions,
and then foams, by using microfluidic systems, namely, microchannel emulsification or
step emulsification. We report a comprehensive experimental investigation of such an
emulsification process occurring at the end of a glass rectangular tube filled with oil and
immersed in a water bath. This allows us to clearly visualize the breakup event of the
dispersed phase liquid finger at the capillary’s end. Below a critical flow rate, the drop size
varies slowly with the flow rate and it is linked to the pinching time of the dispersed phase.
A semiempirical law that gives the resulting drop size as a function of fluid and geometrical
properties is proposed. However, this feature is altered for an aspect ratio of the rectangular
tube below 2.5 where the forming drop hinders the counterflow of the continuous phase
leading to larger drops. Then, above a critical flow rate, or capillary number that weakly
depends on the viscosity ratio of the two liquids, the neck adopts a quasistatic shape well
accounted for by a model based on a Hele-Shaw flow. In that case, drop formation is
driven by gravity and a transition from a dripping regime to a jetting regime is observed
at higher flow rates. Monodisperse foam can also be formed by injecting air. While the
overall dynamics of bubble formation shares similarities with an incompressible fluid, the
bubble size and the critical capillary number do not follow the same scaling laws.
Convective dispersion of particles in a segmented flow
Laboratoire Colloïdes et Matériaux Divisés - Wafa Bouhlel,1,2 S. Danial Naghib,1 Jérôme Bibette,1 and Nicolas Bremond 1
Phys. Rev. Fluids - - DOI: 10.1103/PhysRevFluids.4.104303 - 2019
Convective dispersion of solutes is inherent to flow in channels because of the nonuniformity of the velocity profile. When diffusion is negligible, for large particles for example,
the trajectory of particles can be solely described by a kinematic approach. Here, we
investigate such a phenomenon for micrometer-size beads flowing in a circular pipe. We
show that the presence of large bubbles, namely in the case of a segmented flow, either
prevents the convective dispersion or leads to the accumulation of particles at the rear of
the bubble moving in front. The destabilization of the initially homogeneous suspension
occurs when liquid inertia comes into play. Indeed, for moderate Reynolds number of
the particles, particles move away from the wall, thus exploring different flow lines that
finally impact the axial dispersion features. Moreover, since the bubbles impose an axial
boundary condition of the mean velocity, a net flux of particles directed along the flow
direction is built up above a critical particle Reynolds number. This work is motivated by
the understanding of the flow behavior of biological samples, and especially in the context
of cell encapsulation.
A tuneable microfluidic system for long duration chemotaxis experiments in a 3D collagen matrix
Laboratoire Colloïdes et Matériaux Divisés - Aizel K, Clark AG, Simon A, Geraldo S, Funfak A, Vargas P, Bibette J, Vignjevic DM, Bremond N.
Lab. Chip - 7;17(22): 3851-3861 - DOI: 10.1039/c7lc00649g - 2019
In many cell types, migration can be oriented towards a chemical stimulus. In mammals, for example, embryonic cells migrate to follow developmental cues, immune cells migrate toward sites of inflammation, and cancer cells migrate away from the primary tumour and toward blood vessels during metastasis. Understanding how cells migrate in 3D environments in response to chemical cues is thus crucial to understanding directed migration in normal and disease states. To date, chemotaxis in mammalian cells has been primarily studied using 2D migration models. However, it is becoming increasingly clear that the mechanisms by which cells migrate in 2D and 3D environments dramatically differ, and cells in their native environments are confronted with a complex chemical milieu. To address these issues, we developed a microfluidic device to monitor the behaviour of cells embedded in a 3D collagen matrix in the presence of complex concentration fields of chemoattractants. This tuneable microsystem enables the generation of (1) homogeneous, stationary gradients set by a purely diffusive mechanism, or (2) spatially evolving, stationary gradients, set by a convection-diffusion mechanism. The device allows for stable gradients over several days and is large enough to study the behaviour of large cell aggregates. We observe that primary mature dendritic cells respond uniformly to homogeneous diffusion gradients, while cell behaviour is highly position-dependent in spatially variable convection-diffusion gradients. In addition, we demonstrate a directed response of cancer cells migrating away from tumour-like aggregates in the presence of soluble chemokine gradients. Together, this microfluidic device is a powerful system to observe the response of different cells and aggregates to tuneable chemical gradients.
A new microfluidic approach for the one-step capture, amplification and label-free quantification of bacteria from raw samples
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Iago Pereiro, Amel Bendali, Sanae Tabnaoui, Lucile Alexandre, Jana Srbova, Zuzana Bilkova, Shane Deegan, Lokesh Joshi, Jean-Louis Viovy, Laurent Malaquin, Bruno Dupuy and Stéphanie Descroix
Chem. Sci. - 8(2) 1329-1336 - DOI: 10.1039/C6SC03880H - 2019
A microfluidic method to specifically capture and detect infectious bacteria based on immunorecognition and proliferative power is presented. It involves a microscale fluidized bed in which magnetic and drag forces are balanced to retain antibody-functionalized superparamagnetic beads in a chamber during sample perfusion. Captured cells are then cultivated in situ by infusing nutritionally-rich medium. The system was validated by the direct one-step detection of Salmonella Typhimurium in undiluted unskimmed milk, without pre-treatment. The growth of bacteria induces an expansion of the fluidized bed, mainly due to the volume occupied by the newly formed bacteria. This expansion can be observed with the naked eye, providing simple low-cost detection of only a few bacteria and in a few hours. The time to expansion can also be measured with a low-cost camera, allowing quantitative detection down to 4 cfu (colony forming unit), with a dynamic range of 100 to 107 cfu ml−1 in 2 to 8 hours, depending on the initial concentration. This mode of operation is an equivalent of quantitative PCR, with which it shares a high dynamic range and outstanding sensitivity and specificity, operating at the live cell rather than DNA level. Specificity was demonstrated by controls performed in the presence of a 500× excess of non-pathogenic Lactococcus lactis. The system's versatility was demonstrated by its successful application to the detection and quantitation of Escherichia coli O157:H15 and Enterobacter cloacae. This new technology allows fast, low-cost, portable and automated bacteria detection for various applications in food, environment, security and clinics.
Magnetic fluidized bed for solid phase extraction in microfluidic systems
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Pereiro, Iago ; Tabnaoui, Sanae ; Fermigier, Marc ; du Roure, Olivia ; Descroix, Stephanie ; Viovy, Jean-Louis ; Malaquin, Laurent
Lab. Chip - 17, 9 1603-1615 - DOI: 10.1039/C7LC00063D - 2019
Fluidization, a process in which a granular solid phase behaves like a fluid under the influence of an imposed upward fluid flow, is routinely used in many chemical and biological engineering applications. It brings, to applications involving fluid–solid exchanges, advantages such as high surface to volume ratio, constant mixing, low flow resistance, continuous operation and high heat transfer. We present here the physics of a new miniaturized, microfluidic fluidized bed, in which gravity is replaced by a magnetic field created by an external permanent magnet, and the solid phase is composed of magnetic microbeads with diameters ranging from 1 to 5 μm. These beads can be functionalized with different ligands, catalysts or enzymes, in order to use the fluidized bed as a continuous purification column or bioreactor. It allows flow-through operations at flow rates ranging from 100 nL min−1 up to 5 μL min−1 at low driving pressures (<100 mbar) with intimate liquid/solid contact and a continuous recirculation of beads for enhanced target capture efficiencies. The physics of the system presents significant differences as compared to conventional fluidized beds, which are studied here. The effects of magnetic field profile, flow chamber shape and magnetic bead dipolar interactions on flow regimes are investigated, and the different regimes of operation are described. Qualitative rules to obtain optimal operation are deduced. Finally, an exemplary use as a platform for immunocapture is provided, presenting a limit of detection of 0.2 ng mL−1 for 200 μL volume samples.
The power of solid supports in multiphase and droplet-based microfluidics: towards clinical applications
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Serra, M; Ferraro, D; Pereiro, I; Viovy, J-L; Descroix, S
Lab. Chip - 17 3979-3999 - DOI:10.1039/c7lc00582b - 2019
Multiphase and droplet microfluidic systems are growing in relevance in bioanalytical-related fields, especially due to the increased sensitivity, faster reaction times and lower sample/reagent consumption of many of its derived bioassays. Often applied to homogeneous (liquid/liquid) reactions, innovative strategies for the implementation of heterogeneous (typically solid/liquid) processes have recently been proposed. These involve, for example, the extraction and purification of target analytes from complex matrices or the implementation of multi-step protocols requiring efficient washing steps. To achieve this, solid supports such as functionalized particles (micro or nanometric) presenting different physical properties (e.g. magnetic, optical or others) are used for the binding of specific entities. The manipulation of such supports with different microfluidic principles has both led to the miniaturization of existing biomedical protocols and the development of completely new strategies for diagnostics and research. In this review, multiphase and droplet-based microfluidic systems using solid suspensions are presented and discussed with a particular focus on: i) working principles and technological developments of the manipulation strategies and ii) applications, critically discussing the level of maturity of these systems, which can range from initial proofs of concept to real clinical validations.
Microfluidic model of the platelet-generating organ: beyond bone marrow biomimetics
Laboratoire Microfluidique MEMS et nanostructures - Antoine Blin, Anne Le Goff, Aurélie Magniez, Sonia Poirault-Chassac, Bruno Teste, Géraldine Sicot, Kim Anh Nguyen, Feriel S. Hamdi, Mathilde Reyssat & Dominique Baruch
Nature - Scientific Reports 6 21700 - DOI: 10.1038/srep21700 - 2019
We present a new, rapid method for producing blood platelets in vitro from cultured megakaryocytes based on a microfluidic device. This device consists in a wide array of VWF-coated micropillars. Such pillars act as anchors on megakaryocytes, allowing them to remain trapped in the device and subjected to hydrodynamic shear. The combined effect of anchoring and shear induces the elongation of megakaryocytes and finally their rupture into platelets and proplatelets. This process was observed with megakaryocytes from different origins and found to be robust. This original bioreactor design allows to process megakaryocytes at high throughput (millions per hour). Since platelets are produced in such a large amount, their extensive biological characterisation is possible and shows that platelets produced in this bioreactor are functional.
Micro fl uidic actuators based on temperature-responsive hydrogels
Laboratoire Microfluidique MEMS et nanostructures - Loïc D'Eramo, Benjamin Chollet, Marie Leman, Ekkachai Martwong, Mengxing Li, Hubert Geisler, Jules Dupire, Margaux Kerdraon, Clémence Vergne, Fabrice Monti, Yvette Tran and Patrick Tabeling
- 4 17069 - doi:10.1038/micronano.2017.69 - 2019
The concept of using stimuli-responsive hydrogels to actuatefluids in microfluidic devices is particularly attractive, but limitations,in terms of spatial resolution, speed, reliability and integration, have hindered its development during the past two decades. By patterning and grafting poly(N-isopropylacrylamide) PNIPAM hydrogel films on plane substrates with a 2μm horizontal resolution and closing the system afterward, we have succeeded in unblocking bottlenecks that thermo-sensitive hydrogel technology has
been challenged with until now. In this paper, we demonstrate, for thefi rst time with this technology, devices with up to 7800
actuated micro-cages that sequester and release solutes, along with valves actuated individually with closing and opening switching
times of 0.6 ± 0.1 and 0.25± 0.15 s, respectively. Two applications of this technology are illustrated in the domain of single cell
handling and the nuclear acid amplification test (NAAT) for the Human Synaptojanin 1 gene, which is suspected to be involved in several neurodegenerative diseases such as Parkinson’s disease. The performance of the temperature-responsive hydrogels we
demonstrate here suggests that in association with their moderate costs, hydrogels may represent an alternative to the actuation orhandling techniques currently used in microfluidics, that are, pressure actuated polydimethylsiloxane (PDMS) valves and droplets

Droplet generation at Hele-Shaw microfluidic T-junction
Laboratoire Microfluidique MEMS et nanostructures - I. Chakraborty, J. Ricouvier, P. Yazghur, P. Tabeling, A. Leshansky
Phys. Fluids - 31(2) 22010 - - 2019
Universal diagram for the kinetics of particle deposition in micro channels
Laboratoire Microfluidique MEMS et nanostructures - C.M. Cejas, F. Monti, M. Truchet, J.-P. Burnouf, P. Tabeling
Phys. Rev. E - 98 62606 - - 2019
Universal diagram for the kinetics of particle deposition in micro channels.

391 publications.