Université PSL

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RECHERCHER

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Controlling the distance of highly confined droplets in a capillary by interfacial tension for merging on-demand
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - D. Ferraro, M. Serra, D. Filippi, L. Zago,a E. Guglielmin,a M. Pierno, S. Descroix, J.-L. Viovy and G. Mistura
Hypertension - 74(1) 145-153 - DOI: 10.1161/HYPERTENSIONAHA.118.12380 - 2019
Droplet microfluidics is a powerful technology that finds many applications in chemistry and biomedicine. Among different configurations, droplets confined in a capillary (or plugs) present a number of advantages: they allow positional identification and simplify the integration of complex multi-steps protocols. However, these protocols rely on the control of droplet speed, which is affected by a complex and still debated interplay of various physico-chemical parameters like droplet length, viscosity ratio between droplets and carrier fluid, flow rate and interfacial tension. We present here a systematic investigation of the droplet speed as a function of their length and interfacial tension, and propose a novel, simple and robust methodology to control the relative distance between consecutive droplets flowing in microfluidic channels through the addition of surfactants either into the dispersed and/or into the continuous phases. As a proof of concept application, we present the possibility to accurately trigger in space and time the merging of two confined droplets flowing in a uniform cross-section circular capillary. This approach is further validated by monitoring a conventional enzymatic reaction used to quantify the concentration of H2O2 in a biological sample, showing its potentialities in both continuous and stopped assay methods.
Controlling the distance of highly confined droplets in a capillary by interfacial tension for merging on-demand
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - D. Ferraro, M. Serra, D. Filippi, L. Zago,a E. Guglielmin,a M. Pierno, S. Descroix, J.-L. Viovy and G. Mistura
Lab. Chip - 74(1) 145-153 - DOI: 10.1161/HYPERTENSIONAHA.118.12380 - 2019
Droplet microfluidics is a powerful technology that finds many applications in chemistry and biomedicine. Among different configurations, droplets confined in a capillary (or plugs) present a number of advantages: they allow positional identification and simplify the integration of complex multi-steps protocols. However, these protocols rely on the control of droplet speed, which is affected by a complex and still debated interplay of various physico-chemical parameters like droplet length, viscosity ratio between droplets and carrier fluid, flow rate and interfacial tension. We present here a systematic investigation of the droplet speed as a function of their length and interfacial tension, and propose a novel, simple and robust methodology to control the relative distance between consecutive droplets flowing in microfluidic channels through the addition of surfactants either into the dispersed and/or into the continuous phases. As a proof of concept application, we present the possibility to accurately trigger in space and time the merging of two confined droplets flowing in a uniform cross-section circular capillary. This approach is further validated by monitoring a conventional enzymatic reaction used to quantify the concentration of H2O2 in a biological sample, showing its potentialities in both continuous and stopped assay methods.
Magnetic fluidized bed for solid phase extraction in microfluidic systems†
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Iago Pereiro, ORCID logo ‡abc Sanae Tabnaoui,‡ab Marc Fermigier,d Olivia du Roure,d Stéphanie Descroix,abc Jean-Louis Viovy*abc and Laurent Malaquin
Lab. Chip - 17 1603-1615 - https://doi.org/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 - M. Serra, D. Ferraro, I. Pereiro, J.-L. Viovyabc and S. Descroix
Lab. Chip - 17 3979-3999 - https://doi.org/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.
A new biomimetic assay reveals the temporal role of matrix stiffening in cancer cell invasion
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Ralitza Staneva, Federica Burla, Gijsje H. Koenderink, Stéphanie Descroix, Danijela Matic Vignjevic, Youmna Attieh, and Marine Verhulsel Manuel Théry, Monitoring Editor
Molecular Biology of the Cell - 29 29 - doi.org/10.1091/mbc.E18-01-0068 - 2019
Tumor initiation and growth is associated with significant changes in the surrounding tissue. During carcinoma progression, a global stiffening of the extracellular matrix is observed and is interpreted as a signature of aggressive invasive tumors. However, it is still unknown whether this increase in matrix rigidity promotes invasion and whether this effect is constant along the course of invasion. Here we have developed a biomimetic in vitro assay that enabled us to address the question of the importance of tissue rigidity in the chronology of tumor invasion. Using low concentrations of the sugar threose, we can effectively stiffen reconstituted collagen I matrices and control the stiffening in time with no direct effect on residing cells. Our findings demonstrate that, depending on the timing of its stiffening, the extracellular matrix could either inhibit or promote cancer cell invasion and subsequent metastasis: while matrix stiffening after the onset of invasion promotes cancer cell migration and tumor spreading, stiff matrices encapsulate the tumor at an early stage and prevent cancer cell invasion. Our study suggests that adding a temporal dimension in in vitro models to analyze biological processes in four dimensions is necessary to fully capture their complexity.
Redox-Triggered Control of Cell Adhesion and Deadhesion on Poly(lysine)-g-poly(ethylene oxide) Adlayers
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Louise Hespel, Julien Dupré de Baubigny, Pierre Lalanne, Simon de Beco, Mathieu Coppey, Catherine Villard, Vincent Humblot, Emmanuelle Marie, and Christophe Tribet
ACS Appl. Bio Mater - 10 4367-4376 - doi.org/10.1021/acsabm.9b00601 - 2019
Spontaneous adsorption of poly(lysine)-g-poly(ethylene glycol) comb-like copolymers (PLL-g-PEG) is a versatile mean to coat substrates with polymer layers that resist cell adhesion. We prepared redox cleavable PLL-g-PEG to switch adhesion on demand. Redox sensitivity was obtained by introducing disulfide linkers between the PLL backbone and PEG strands. This modification was done alone or in combination with an azide end on the PEG strands that enabled in situ conjugations of adhesion peptides or fluorescent labels (by a simple application of commercially available molecules for copper-free click chemistry compatible with cell survival). To balance the functional (adhesion-promoting) vs cell-repellent copolymers, mixed layers of adjusted compositions were obtained by coadsorption from mixed solutions of the cleavable copolymer with noncleavable and repellant PLL-g-PEG. The deposition of copolymers and quantitative cleavage as triggered by reductive conditions (application of solutions of tris(carboxyethyl)phosphine, dithiothreitol, or glutathione) were characterized by QCM-D, XPS, and fluorescence microscopy. In cell culture conditions, redox-triggered cleavage was obtained by a nontoxic application of TCEP for a few minutes, enabling either to release cell attachment points (i.e., cleavage of RGD-presenting areas) or to “open” nonspecific adherent areas (i.e., transition from PEG-presenting areas to adherent PLL-like coatings).
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.
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.
Foam as a self-assembling amorphous photonic band gap material
Laboratoire Microfluidique MEMS et nanostructures - View ORCID ProfileJoshua Ricouvier, Patrick Tabeling, and Pavel Yazhgur
Phys. Fluids - 116 (19) 9202-9207 - doi.org/10.1073/pnas.1820526116 - 2019
We show that slightly polydisperse disordered 2D foams can be used as a self-assembled template for isotropic photonic band gap (PBG) materials for transverse electric (TE) polarization. Calculations based on in-house experimental and simulated foam structures demonstrate that, at sufficient refractive index contrast, a dry foam organization with threefold nodes and long slender Plateau borders is especially advantageous to open a large PBG. A transition from dry to wet foam structure rapidly closes the PBG mainly by formation of bigger fourfold nodes, filling the PBG with defect modes. By tuning the foam area fraction, we find an optimal quantity of dielectric material, which maximizes the PBG in experimental systems. The obtained results have a potential to be extended to 3D foams to produce a next generation of self-assembled disordered PBG materials, enabling fabrication of cheap and scalable photonic devices.
Fibrin-Targeted Polymerized Shell Microbubbles as Potential Theranostic Agents for Surgical Adhesions
Laboratoire Microfluidique MEMS et nanostructures - Catherine A. Gormley, Benjamin J. Keenan, Jo Ann Buczek-Thomas,† Amanda C. S. N. Pessoa, Jiang Xu, Fabrice Monti, Patrick Tabeling, R. Glynn Holt, Jon O. Nagy, and Joyce Y. Wong
Langmuir - 35(31) 10061–10067 - doi: 10.1021/acs.langmuir.8b03692 - 2019
The development of new therapies for surgical adhesions has proven to be difficult as there is no consistently effective way to assess treatment efficacy in clinical trials without performing a second surgery, which can result in additional adhesions. We have developed lipid microbubble formulations that use a short peptide sequence, CREKA, to target fibrin, the molecule that forms nascent adhesions. These targeted polymerized shell microbubbles (PSMs) are designed to allow ultrasound imaging of early adhesions for diagnostic purposes and for evaluating the success of potential treatments in clinical trials while acting as a possible treatment. In this study, we show that CREKA-targeted microbubbles preferentially bind fibrin over fibrinogen and are stable for long periods of time (~48 h), that these bound microbubbles can be visualized by ultrasound, and that neither these lipid-based bubbles nor their diagnostic-ultrasound-induced vibrations damage mesothelial cells in vitro. Moreover, these bubbles show the potential to identify adhesionlike fibrin formations and may hold promise in blocking or breaking up fibrin formations in vivo.

Deposition kinetics of bi- and tridisperse colloidal suspensions in microchannels under the van der Waals regime
Laboratoire Microfluidique MEMS et nanostructures - Cesare M. Cejas, Lucrezia Maini, Fabrice Montia and Patrick Tabeling
Soft Matter - 15 7438-7447 - doi.org/10.1039/C9SM01098J - 2019
We investigate the kinetics of irreversible adsorption under the van der Waals regime, i.e. weakly Brownian polydisperse colloidal suspensions injected into shallow microchannels at high ionic strengths, where each suspension is represented by populations of particles with different particle sizes. We find that each population size of the particle in the suspension can be treated independently using an analytical solution based on the advection–diffusion equation and that the distribution of the adsorbed particles along the channel axis behaves according to a power law. The experimental measurements agree with Langevin simulations and are well accounted for by theory valid in the van der Waals regime. Operating in the van der Waals regime permits the present study to confirm the use of microfluidics as an effective in situ method to measure the Hamaker constant of particles under aqueous conditions.

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 - DOI: 10.1063/1.5086808 - 2019
Pairwise frictional profile between particles determines discontinuous shear thickening transition in non‐colloidal suspensions
Laboratoire Micromégas - J. Comtet, G. Chatté, A. Niguès, L. Bocquet, A. Siria, and A. Colin
Nat Commun - 8 15633 - DOI: 10.1038/ncomms15633 - 2019
The process by which sheared suspensions go through a dramatic change in viscosity is known as discontinuous shear thickening. Although well-characterized on the macroscale, the microscopic mechanisms at play in this transition are still poorly understood. Here, by developing new experimental procedures based on quartz-tuning fork atomic force microscopy, we measure the pairwise frictional profile between approaching pairs of polyvinyl chloride and cornstarch particles in solvent. We report a clear transition from a low-friction regime, where pairs of particles support a finite normal load, while interacting purely hydrodynamically, to a high-friction regime characterized by hard repulsive contact between the particles and sliding friction. Critically, we show that the normal stress needed to enter the frictional regime at nanoscale matches the critical stress at which shear thickening occurs for macroscopic suspensions. Our experiments bridge nano and macroscales and provide long needed demonstration of the role of frictional forces in discontinuous shear thickening.
Entrance Effects in Concentration-Gradient-Driven Flow Through an Ultrathin Porous Membrane
Laboratoire Micromégas - Daniel J. Rankin, Lydéric Bocquet, David M. Huang
J. Chem. Phys - 151 44705 - DOI:10.1063/1.5108700 - 2019
Transport of liquid mixtures through porous membranes is central to processes such as desalination, chemical separations and energy harvesting, with ultrathin membranes made from novel 2D nanomaterials showing exceptional promise. Here we derive, for the first time, general equations for the solution and solute fluxes through a circular pore in an ultrathin planar membrane induced by a solute concentration gradient. We show that the equations accurately capture the fluid fluxes measured in finite-element numerical simulations for weak solute-membrane interactions. We also derive scaling laws for these fluxes as a function of the pore size and the strength and range of solute-membrane interactions. These scaling relationships differ markedly from those for concentration-gradient-driven flow through a long cylindrical pore or for flow induced by a pressure gradient or electric field through a pore in an ultrathin membrane. These results have broad implications for transport of liquid mixtures through membranes with a thickness on the order of the characteristic pore size.
Osmosis, from molecular insights to large-scale applications
Laboratoire Micromégas - Sophie Marbach, Lyderic Bocquet
Phys. Chem. - 48 3102-3144 - DOI:10.1039/C8CS00420J - 2019
Osmosis is a universal phenomenon occurring in a broad variety of processes and fields. It is the archetype of entropic forces, both trivial in its fundamental expression - the van 't Hoff perfect gas law - and highly subtle in its physical roots. While osmosis is intimately linked with transport across membranes, it also manifests itself as an interfacial transport phenomenon: the so-called diffusio-osmosis and -phoresis, whose consequences are presently actively explored for example for the manipulation of colloidal suspensions or the development of active colloidal swimmers. Here we give a global and unifying view of the phenomenon of osmosis and its consequences with a multi-disciplinary perspective. Pushing the fundamental understanding of osmosis allows to propose new perspectives for different fields and we highlight a number of examples along these lines, for example introducing the concepts of osmotic diodes, active separation and far from equilibrium osmosis, raising in turn fundamental questions in the thermodynamics of separation. The applications of osmosis are also obviously considerable and span very diverse fields. Here we discuss a selection of phenomena and applications where osmosis shows great promises: osmotic phenomena in membrane science (with recent developments in separation, desalination, reverse osmosis for water purification thanks in particular to the emergence of new nanomaterials); applications in biology and health (in particular discussing the kidney filtration process); osmosis and energy harvesting (in particular, osmotic power and blue energy as well as capacitive mixing); applications in detergency and cleaning, as well as for oil recovery in porous media.
Molecular streaming and its voltage control in ångström-scale channels
Laboratoire Micromégas - Timothée Mouterde, Anthony R. Poggioli, Ashok Keerthi, Shafat Hussain Dar
Nature - 567(7746) 87-90 - DOI: 10.1038/s41586-019-0961-5 - 2019
Over the past decade, the ability to reduce the dimensions of fluidic devices to the nanometre scale (by using nanotubes1–5 or nanopores6–11, for example) has led to the discovery of unexpected water- and ion-transport phenomena12–14. More recently, van der Waals assembly of two-dimensional materials¹⁵ has allowed the creation of artificial channels with ångström-scale precision¹⁶. Such channels push fluid confinement to the molecular scale, wherein the limits of continuum transport equations¹⁷ are challenged. Water films on this scale can rearrange into one or two layers with strongly suppressed dielectric permittivity18,19 or form a room-temperature ice phase²⁰. Ionic motion in such confined channels²¹ is affected by direct interactions between the channel walls and the hydration shells of the ions, and water transport becomes strongly dependent on the channel wall material²². We explore how water and ionic transport are coupled in such confinement. Here we report measurements of ionic fluid transport through molecular-sized slit-like channels. The transport, driven by pressure and by an applied electric field, reveals a transistor-like electrohydrodynamic effect. An applied bias of a fraction of a volt increases the measured pressure-driven ionic transport (characterized by streaming mobilities) by up to 20 times. This gating effect is observed in both graphite and hexagonal boron nitride channels but exhibits marked material-dependent differences. We use a modified continuum framework accounting for the material-dependent frictional interaction of water molecules, ions and the confining surfaces to explain the differences observed between channels made of graphene and hexagonal boron nitride. This highly nonlinear gating of fluid transport under molecular-scale confinement may offer new routes to control molecular and ion transport, and to explore electromechanical couplings that may have a role in recently discovered mechanosensitive ionic channels²³.
Beyond the Trade-Off: Dynamic Selectivity in Ionic Transport and Current Rectification
Laboratoire Micromégas - A. Poggioli, A. Siria, L. Bocquet
Phys. Chem. - 123.5 1171-1185 - doi.org/10.1021/acs.jpcb.8b11202 - 2019
Traditionally, ion selectivity in nanopores and nanoporous membranes is understood to be a consequence of Debye overlap, in which the Debye screening length is comparable to the nanopore radius somewhere along the length of the nanopore(s). This criterion sets a significant limitation on the size of ion-selective nanopores, as the Debye length is on the order of 1–10 nm for typical ionic concentrations. However, the analytical results we present here demonstrate that surface conductance generates a dynamical selectivity in ion transport, and this selectivity is controlled by so-called Dukhin, rather than Debye, overlap. The Dukhin length, defined as the ratio of surface to bulk conductance, reaches values of hundreds of nanometers for typical surface charge densities and ionic concentrations, suggesting the possibility of designing large-nanopore (10–100 nm), high-conductance membranes exhibiting significant ion selectivity. Such membranes would have potentially dramatic implications for the efficiency of osmotic energy conversion and separation techniques. Furthermore, we demonstrate that this mechanism of dynamic selectivity leads ultimately to the rectification of ionic current, rationalizing previous studies, showing that Debye overlap is not a necessary condition for the occurrence of rectifying behavior in nanopores.
Atomic rheology of gold nanojunctions
Laboratoire Micromégas - Jean Comtet, Antoine Lainé, Antoine Niguès, Lydéric Bocquet & Alessandro Siria
Nature - 569(7756) 393–397 - DOI : 10.1038/s41586-019-1178-3 - 2019
Despite extensive investigations of dissipation and deformation processes in micro- and nano-sized metallic samples1,2,3,4,5,6,7, the mechanisms at play during the deformation of systems with ultimate (molecular) size remain unknown. Although metallic nanojunctions, which are obtained by stretching metallic wires down to the atomic level, are typically used to explore atomic-scale contacts5,8,9,10,11, it has not been possible until now to determine the full equilibrium and non-equilibrium rheological flow properties of matter at such scales. Here, by using an atomic-force microscope equipped with a quartz tuning fork, we combine electrical and rheological measurements on ångström-size gold junctions to study the non-linear rheology of this model atomic system. By subjecting the junction to increasing subnanometric deformations we observe a transition from a purely elastic regime to a plastic one, and eventually to a viscous-like fluidized regime, similar to the rheology of soft yielding materials12,13,14, although orders of magnitude different in length scale. The fluidized state furthermore exhibits capillary attraction, as expected for liquid capillary bridges. This shear fluidization cannot be captured by classical models of friction between atomic planes15,16 and points to an unexpected dissipative behaviour of defect-free metallic junctions at ultimate scales. Atomic rheology is therefore a powerful tool that can be used to probe the structural reorganization of atomic contacts.

Ionic Coulomb blockade as a fractional Wien effect
Laboratoire Micromégas - Nikita Kavokine, Sophie Marbach, Alessandro Siria & Lydéric Bocquet
Nat. Nanotechnol. - 14 573–578 - doi.org/10.1038/s41565-019-0425-y - 2019
Recent advances in nanofluidics have allowed the exploration of ion transport down to molecular-scale confinement, yet artificial porins are still far from reaching the advanced functionalities of biological ion machinery. Achieving single ion transport that is tunable by an external gate—the ionic analogue of electronic Coulomb blockade—would open new avenues in this quest. However, an understanding of ionic Coulomb blockade beyond the electronic analogy is still lacking. Here, we show that the many-body dynamics of ions in a charged nanochannel result in quantized and strongly nonlinear ionic transport, in full agreement with molecular simulations. We find that ionic Coulomb blockade occurs when, upon sufficient confinement, oppositely charged ions form ‘Bjerrum pairs’, and the conduction proceeds through a mechanism reminiscent of Onsager’s Wien effect. Our findings open the way to novel nanofluidic functionalities, such as an ion pump based on ionic Coulomb blockade, inspired by its electronic counterpart.
MicroMegascope based dynamic surface force apparatus
Laboratoire Micromégas - Lainé, Antoine; Jubin, Laetitia; Canale, Luca; Bocquet, Lydéric; Siria, Alessandro; Donaldson, Stephen H., Jr.; Niguès, Antoine
Nanotechnology - 30 195502 - DOI: 10.1088/1361-6528/ab02ba - 2019
Surface force apparatus (SFA) allows accurate resolving of the interfacial properties of fluids confined between extended surfaces. The accuracy of the SFA makes it an ubiquitous tool for the nanoscale mechanical characterization of soft matter systems. The SFA traditionally measures force-distance profiles through interferometry with subnanometric distance precision. However, these techniques often require a dedicated and technically demanding experimental setup, and there remains a need for versatile and simple force-distance measurement tools. Here we present a MicroMegascope based dynamic SFA capable of accurate measurement of the dynamic force profile of a liquid confined between a millimetric sphere and a planar substrate. Normal and shear mechanical impedance is measured within the classical frequency modulation framework. We measure rheological and frictional properties from micrometric to molecular confinement. We also highlight the resolution of small interfacial features such as ionic liquid layering. This apparatus shows promise as a versatile force-distance measurement device for exotic surfaces or extreme environments.

515 publications.