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Toward a Rational Design of Titanium Metal-Organic Frameworks
Laboratoire Institut des Matériaux Poreux de Paris - Author links open overlay panelSujingWang128HelgeReinsch3NicolasHeymans4MohammadWahiduzzaman5CharlotteMartineau-Corcos67GuyDe Weireld4GuillaumeMaurin5ChristianSerre1
MATTER - 2(2) 440-450 - https://doi.org/10.1016/j.matt.2019.11.002 - 2020
Rational design and synthesis of metal-organic frameworks (MOFs) is of particular interest in fine-tuning the crystalline structures for given targeting applications. Considerable advance of this topic has been achieved for MOFs built with a large number of metal species but not titanium. The complex and unpredictable titanium chemistry in solution not only leads to the difficulty of isolating crystalline Ti-MOFs via direct synthesis but also results in the challenge of maintaining control over ordered structures. We demonstrated a Ti-O cluster guided green scalable preparation of a Ti-MOF (MIP-207) in a controlled manner with both post-synthetic and one-pot reaction routes. The chemical environment and functionality of the MOF structural void could be easily tuned by adopting the mixed-linker strategy, which finally resulted in an adjustable performance in CO2 capture over N2. This provides a new avenue for the rational design of Ti-MOFs in energy- and environment-related applications.
Highly Porous Hybrid Metal–Organic Nanoparticles Loaded with Gemcitabine Monophosphate: a Multimodal Approach to Improve Chemo‐ and Radiotherapy
Laboratoire Institut des Matériaux Poreux de Paris - Dr. Xue Li Dr. Erika Porcel Dr. Mario Menendez‐Miranda Jingwen Qiu Xiaomin Yang Dr. Christian Serre Alexandra Pastor Dr. Didier Desmaële
ChemMedChem - 15(3) - https://doi.org/10.1002/cmdc.201900596 - 2020
Nanomedicine recently emerged as a novel strategy to improve the performance of radiotherapy. Herein we report the first application of radioenhancers made of nanoscale metal‐organic frameworks (nanoMOFs), loaded with gemcitabine monophosphate (Gem‐MP), a radiosensitizing anticancer drug. Iron trimesate nanoMOFs possess a regular porous structure with oxocentered Fe trimers separated by around 5 Å (trimesate linkers). This porosity is favorable to diffuse the electrons emitted from nanoMOFs due to activation by γ radiation, leading to water radiolysis and generation of hydroxyl radicals which create nanoscale damages in cancer cells. Moreover, nanoMOFs act as “Trojan horses”, carrying their Gem‐MP cargo inside cancer cells to interfere with DNA repair. By displaying different mechanisms of action, both nanoMOFs and incorporated Gem‐MP contribute to improve radiation efficacy. The radiation enhancement factor of Gem‐MP loaded nanoMOFs reaches 1.8, one of the highest values ever reported. These results pave the way toward the design of engineered nanoparticles in which each component plays a role in cancer treatment by radiotherapy.
Methanol and Humidity Capacitive Sensors Based on Thin Films of MOF Nanoparticles
Laboratoire Institut des Matériaux Poreux de Paris - Miguel A. Andrés, Mani Teja Vijjapu, Sandeep G. Surya, Osama Shekhah, Khaled Nabil Salama, Christian Serre, Mohamed Eddaoudi, Olivier Roubeau, and Ignacio Gascón
ACS Publications - 12(3) 4155–4162 - https://doi.org/10.1021/acsami.9b20763 - 2020
The successful development of modern gas sensing technologies requires high sensitivity and selectivity coupled to cost effectiveness, which implies the necessity to miniaturize devices while reducing the amount of sensing material. The appealing alternative of integrating nanoparticles of a porous metal–organic framework (MOF) onto capacitive sensors based on interdigitated electrode (IDE) chips is presented. We report the deposition of MIL-96(Al) MOF thin films via the Langmuir–Blodgett (LB) method on the IDE chips, which allowed the study of their gas/vapor sensing properties. First, sorption studies of several organic vapors like methanol, toluene, chloroform, etc. were conducted on bulk MOF. The sorption data revealed that MIL-96(Al) presents high affinity toward water and methanol. Later on, ordered LB monolayer films of MIL-96(Al) particles of ∼200 nm were successfully deposited onto IDE chips with homogeneous coverage of the surface in comparison to conventional thin film fabrication techniques such as drop-casting. The sensing tests showed that MOF LB films were selective for water and methanol, and short response/recovery times were achieved. Finally, chemical vapor deposition (CVD) of a porous thin film of Parylene C (thickness ∼250–300 nm) was performed on top of the MOF LB films to fabricate a thin selective layer. The sensing results showed an increase in the water selectivity and sensitivity, while those of methanol showed a huge decrease. These results prove the feasibility of the LB technique for the fabrication of ordered MOF thin films onto IDE chips using very small MOF quantities.
Hexane isomers separation on an isoreticular series of microporous Zr carboxylate metal organic frameworks
Laboratoire Institut des Matériaux Poreux de Paris - Adriano Henrique, Tanmoy Maity, Hengli Zhao, de Pedro F. Brântuas, Alírio E. Rodrigues, Farid Nouar, Aziz Ghoufi, Guillaume Maurin, José A. C. Silva and Christian Serre
journal of materials chemistry A - 8 17780-17789 - https://doi.org/10.1039/D0TA05538G - 2020
A series of isoreticular Zr carboxylate MOFs, MIL-140A, B and C, exhibiting 1D microporous triangular shaped channels and based on different aromatic dicarboxylate ligands (1,4-BDC, 2,6-NDC and 4,4′-BPDC, respectively), were investigated by chromatographic breakthrough experiments regarding their ability to separate hexane isomers (nC6/2MP/3MP/23DMB/22DMB). Both single and equimolar multicomponent experiments were performed at the temperatures 343, 373, and 423 K and a total hydrocarbon pressure up to 50.0 kPa using the MIL-140B form. The elution order is similar to that of the normal boiling point of the compounds nC6 > 2MP > 3MP > 23DMB > 22DMB. It is noteworthy that this material enables separation of the hexane isomers by class, linear > mono-branched > di-branched, with a selectivity (linear + mono-branched isomers/di-branched isomers) up to 10 at 343 K, decreasing, however, as the temperature increases. Grand canonical Monte Carlo simulations were further performed to gain insight into the adsorption/separation mechanisms, highlighting the crucial need to consider a tiny tilting of the organic linkers for capturing the experimental observations. The impact of the pore size was finally assessed through the comparison with MIL-140A and MIL-140C, respectively, based on multicomponent experiments at 343 K. We evidenced a significant decrease of the selectivity (about 2) in both cases while the loadings were decreased or increased for MIL-140A and MIL-140C, respectively. Additionally, MIL-140C was demonstrated to exhibit an uncommon shift in the elution order occurring between nC6 and 3MP, 3MP being the last compound to saturate in the column.
First Example of Protonation of Ruddlesden–Popper Sr 2 IrO 4 : A Route to Enhanced Water Oxidation Catalysts
Laboratoire Institut des Matériaux Poreux de Paris - Ronghuang Zhang, Paul E. Pearce, Vanessa Pimenta, Jordi Cabana, Heifang Li, Daniel Alves Dalla Corte, Artem M. Abakumov, Gwenaëlle Rousse, Domitille Giaume, Michael Deschamps, and Alexis Grimaud
Chemistry of Materials, American Chemical Society - 32 (8) 3499-3509 - https://doi.org/10.1021/acs.chemmater.0c00432 - 2020
Water electrolysis is considered to be a promising way to store and convert excess renewable energies into hydrogen, which is of high value for many chemical transformation processes such as the Haber-Bosch process. The main challenge to promote the deployment of the polymer electrolyte membrane water electrolysis (PEMWE) technology lies in the design of robust catalysts for the oxygen evolution reaction (OER) under acidic conditions, since most of the transition metal-based oxides undergo structural degradation under these harsh acidic conditions. To broaden the variety of candidate materials as OER catalysts, a cation-exchange synthetic route was recently explored to reach crystalline pronated iridates with unique structural properties and stability. In this work, a new protonated phase H3.6IrO4·3.7H2O, prepared via Sr2+/H+ cation exchange at room temperature starting from the parent Ruddlesden–Popper Sr2IrO4 phase, is described. This is the first discovery of crystalline protonated iridate forming from a perovskite-like phase, adopting a layered structure with apex-linked IrO6 octahedra. Furthermore, H3.6IrO4·3.7H2O is found to possess not only an enhanced specific catalytic activity, superior to that of other perovskite-based iridates, but also a mass activity comparable to that of nanosized IrOx particles, while showing an improved catalytic stability owing to its ability to reversibly exchange protons in acid.
Revealing the Impact of Electrolyte Composition for Co-Based Water Oxidation Catalysts by the Study of Reaction Kinetics Parameters
Laboratoire Institut des Matériaux Poreux de Paris - Yan Duan, Nicolas Dubouis, Jiaqiang Huang, Daniel Alves Dalla Corte, Vanessa Pimenta, Zhichuan J. Xu, and Alexis Grimaud
ACS Publications - 7 4160–4170 - https://doi.org/10.1021/acscatal.0c00490 - 2020
Recent studies have revealed the critical role played by the electrolyte composition on the oxygen evolution reaction (OER) kinetics on the surface of highly active catalysts. While numerous works were devoted to understand the effect of the electrolyte composition on the physical properties of the catalysts’ surface, very little is known yet about its exact impact on the OER kinetics parameters. In this work, we reveal that the origin for the electrolyte-dependent OER activity for Co-based catalysts originates from two different effects. Increasing the alkaline electrolyte concentration for La1–xSrxCoO3−δ perovskites with x > 0 and for amorphous CoOOH increases the pre-exponential factor, which can be explained either by an increase of the concentration of active sites or by a change in the entropy of activation. However, changing the alkali cation results in a decrease of the apparent activation enthalpy for Fe-containing amorphous films, traducing a change in intermediates’ binding energies.
Machine Learning to Improve the Sensing of Biomolecules by Conical Track-Etched Nanopore
Laboratoire Institut des Matériaux Poreux de Paris - Nathan Meyer, Jean-Marc Janot , Mathilde Lepoitevin , Michaël Smietana ,Jean-Jacques Vasseur ,Joan Torrent and Sébastien Balme
Biosensors - 10(10) 140 - https://doi.org/10.3390/bios10100140 - 2020
Single nanopore is a powerful platform to detect, discriminate and identify biomacromolecules. Among the different devices, the conical nanopores obtained by the track-etched technique on a polymer film are stable and easy to functionalize. However, these advantages are hampered by their high aspect ratio that avoids the discrimination of similar samples. Using machine learning, we demonstrate an improved resolution so that it can identify short single- and double-stranded DNA (10- and 40-mers). We have characterized each current blockade event by the relative intensity, dwell time, surface area and both the right and left slope. We show an overlap of the relative current blockade amplitudes and dwell time distributions that prevents their identification. We define the different parameters that characterize the events as features and the type of DNA sample as the target. By applying support-vector machines to discriminate each sample, we show accuracy between 50% and 72% by using two features that distinctly classify the data points. Finally, we achieved an increased accuracy (up to 82%) when five features were implemented.
Metabolic cost of rapid adaptation of single yeast cells
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Gabrielle Woronoff, Philippe Nghe, Jean Baudry, Laurent Boitard, Erez Braun, Andrew D. Griffiths, and Jérôme Bibette
PNAS - 117 (20) 10660-10666 - https://doi.org/10.1073/pnas.1913767117 - 2020
Cells can rapidly adapt to changing environments through nongenetic processes; however, the metabolic cost of such adaptation has never been considered. Here we demonstrate metabolic coupling in a remarkable, rapid adaptation process (1 in 1,000 cells adapt per hour) by simultaneously measuring metabolism and division of thousands of individual Saccharomyces cerevisiae cells using a droplet microfluidic system: droplets containing single cells are immobilized in a two-dimensional (2D) array, with osmotically induced changes in droplet volume being used to measure cell metabolism, while simultaneously imaging the cells to measure division. Following a severe challenge, most cells, while not dividing, continue to metabolize, displaying a remarkably wide diversity of metabolic trajectories from which adaptation events can be anticipated. Adaptation requires a characteristic amount of energy, indicating that it is an active process. The demonstration that metabolic trajectories predict a priori adaptation events provides evidence of tight energetic coupling between metabolism and regulatory reorganization in adaptation. This process allows S. cerevisiae to adapt on a physiological timescale, but related phenomena may also be important in other processes, such as cellular differentiation, cellular reprogramming, and the emergence of drug resistance in cancer.
High-throughput single-cell activity-based screening and sequencing of antibodies using droplet microfluidics
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Annabelle Gérard, Adam Woolfe, […]Colin Brenan
Nat Biotechnol. - 38 715–721 - https://doi.org/10.1038/s41587-020-0466-7 - 2020
Mining the antibody repertoire of plasma cells and plasmablasts could enable the discovery of useful antibodies for therapeutic or research purposes1. We present a method for high-throughput, single-cell screening of IgG-secreting primary cells to characterize antibody binding to soluble and membrane-bound antigens. CelliGO is a droplet microfluidics system that combines high-throughput screening for IgG activity, using fluorescence-based in-droplet single-cell bioassays2, with sequencing of paired antibody V genes, using in-droplet single-cell barcoded reverse transcription. We analyzed IgG repertoire diversity, clonal expansion and somatic hypermutation in cells from mice immunized with a vaccine target, a multifunctional enzyme or a membrane-bound cancer target. Immunization with these antigens yielded 100–1,000 IgG sequences per mouse. We generated 77 recombinant antibodies from the identified sequences and found that 93% recognized the soluble antigen and 14% the membrane antigen. The platform also allowed recovery of ~450–900 IgG sequences from ~2,200 IgG-secreting activated human memory B cells, activated ex vivo, demonstrating its versatility.
Quantitative modeling of the effect of antigen dosage on B-cell affinity distributions in maturating germinal centers
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Marco Molari, Klaus Eyer, Jean Baudry, Simona Cocco, Rémi Monasson
e-Life - 1 619 - DOI: 10.7554/eLife.55678 - 2020
Affinity maturation is a complex dynamical process allowing the immune system to generate antibodies capable of recognizing antigens. We introduce a model for the evolution of the distribution of affinities across the antibody population in germinal centers. The model is amenable to detailed mathematical analysis and gives insight on the mechanisms through which antigen availability controls the rate of maturation and the expansion of the antibody population. It is also capable, upon maximum-likelihood inference of the parameters, to reproduce accurately the distributions of affinities of IgG-secreting cells we measure in mice immunized against Tetanus Toxoid under largely varying conditions (antigen dosage, delay between injections). Both model and experiments show that the average population affinity depends non-monotonically on the antigen dosage. We show that combining quantitative modeling and statistical inference is a concrete way to investigate biological processes underlying affinity maturation (such as selection permissiveness), hardly accessible through measurements.
The impact of frost-damage on the quality and quantity of the secreted antigen-specific IgG repertoire
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Magda Rybczynska, Jean Baudry, Eyer Klaus
ELSEVIER - 38 5337-5342 - https://doi.org/10.1016/j.vaccine.2020.05.066 - 2020
Freezing of alum-based vaccines drastically alters their colloidal composition and leads to irreversible cluster formation. The loss of stability is well described, but the impact of frost damage on the functionality of the induced and secreted antibody repertoire has not been studied in detail. We therefore applied our single-cell measurement platform to extract the frequencies of Immunoglobulin G-secreting cells in combination with individual secretion rates and affinities. We showed that, frost-damaged or not, the tested vaccine was able to generate similar frequencies of total and antigen-affine IgG-secreting cells. Additionally, the frost-damaged vaccine stimulated a similar T-cell cytokine secretion pattern when compared to the regularly stored vaccine. However, frost-damaged vaccines induced no efficient affinity maturation and a complete collapse of the affinity distribution was observed. This study unveiled the impact of frost-damage to alum-based vaccines on the induced secreted antibody repertoire, and illustrated the power of functional single-antibody analysis.
The Quantitative Assessment of the Secreted IgG Repertoire after Recall to Evaluate the Quality of Immunizations
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Klaus Eyer, Carlos Castrillon, Guilhem Chenon, Jérôme Bibette, Pierre Bruhns, Andrew D. Griffiths and Jean Baudry
Nat Immunol. - 9 205 - doi.org/10.4049/jimmunol.2000112 - 2020
One of the major goals of vaccination is to prepare the body to rapidly secrete specific Abs during an infection. Assessment of the vaccine quality is often difficult to perform, as simple measurements like Ab titer only partly correlate with protection. Similarly, these simple measurements are not always sensitive to changes in the preceding immunization scheme. Therefore, we introduce in this paper a new, to our knowledge, method to assay the quality of immunization schemes for mice: shortly after a recall with pure Ag, we analyze the frequencies of IgG-secreting cells (IgG-SCs) in the spleen, as well as for each cells, the Ag affinity of the secreted Abs. We observed that after recall, appearance of the IgG-SCs within the spleen of immunized mice was fast (<24 h) and this early response was free of naive IgG-SCs. We further confirmed that our phenotypic analysis of IgG-SCs after recall strongly correlated with the different employed immunization schemes. Additionally, a phenotypic comparison of IgG-SCs presented in the spleen during immunization or after recall revealed similarities but also significant differences. The developed approach introduced a novel (to our knowledge), quantitative, and functional highly resolved alternative to study the quality of immunizations.
In vitro bone metastasis dwelling in a 3D bioengineered niche.
Laboratoire Macromolécules et Microsystèmes en Biologie et Médecine - Han W, El Botty R, Montaudon E, Malaquin L, Deschaseaux F, Espagnolle N, Marangoni E, Cottu P, Zalcman G, Parrini MC, Assayag F, Sensebe L, Silberzan P, Vincent-Salomon A, Dutertre G, Roman-Roman S, Descroix S, Camonis J
Biomaterials - 269 120624 - DOI: 10.1016/j.biomaterials.2020.120624 - 2020
Bone is the most frequent metastasis site for breast cancer. As well as dramatically increasing disease burden, bone metastases are also an indicator of poor prognosis. One of the main challenges in investigating bone metastasis in breast cancer is engineering in vitro models that replicate the features of in vivo bone environments. Such in vitro models ideally enable the biology of the metastatic cells to mimic their in vivo behavior as closely as possible. Here, taking benefit of cutting-edge technologies both in microfabrication and cancer cell biology, we have developed an in vitro breast cancer bone-metastasis model. To do so we first 3D printed a bone scaffold that reproduces the trabecular architecture and that can be conditioned with osteoblast-like cells, a collagen matrix, and mineralized calcium. We thus demonstrated that this device offers an adequate soil to seed primary breast cancer bone metastatic cells. In particular, patient-derived xenografts being considered as a better approach than cell lines to achieve clinically relevant results, we demonstrate the ability of this biomimetic bone niche model to host patient-derived xenografted metastatic breast cancer cells. These patient-derived xenograft cells show a long-term survival in the bone model and maintain their cycling propensity, and exhibit the same modulated drug response as in vivo. This experimental system enables access to the idiosyncratic features of the bone microenvironment and cancer bone metastasis, which has implications for drug testing.
Integration of a soft dielectric composite into a cantilever beam for mechanical energy harvesting, comparison between capacitive and triboelectric transducers
Laboratoire Matériaux Innovants pour l'Energie - Mickaël Pruvost, Wilbert J. Smit, Cécile Monteux, Pablo Del Corro, Isabelle Dufour, Cédric Ayela, Philippe Poulin & Annie Colin
Scientific Reports - 10 20681 - - 2020
Flexible dielectrics that harvest mechanical energy via electrostatic effects are excellent candidates as power sources for wearable electronics or autonomous sensors. The integration of a soft dielectric composite (polydimethylsiloxane PDMS-carbon black CB) into two mechanical energy harvesters is here presented. Both are based on a similar cantilever beam but work on different harvesting principles: variable capacitor and triboelectricity. We show that without an external bias the triboelectric beam harvests a net density power of 0.3 μW/cm2 under a sinusoidal acceleration of 3.9g at 40 Hz. In a variable capacitor configuration, a bias of 0.15 V/μm is required to get the same energy harvesting performance under the same working conditions. As variable capacitors’ harvesting performance are quadratically dependent on the applied bias, increasing the bias allows the system to harvest energy much more efficiently than the triboelectric one. The present results make CB/PDMS composites promising for autonomous portable multifunctional systems and intelligent sensors.
Emulsion Destabilization by Squeeze Flow
Laboratoire Matériaux Innovants pour l'Energie - Riande I Dekker, Antoine Deblais, Krassimir P Velikov , Peter Veenstra , Annie Colin , Hamid Kellay , Willem K Kegel , Daniel Bonn
Langmuir - 36(27) 7795-7800 - doi: 10.1021/acs.langmuir.0c00759 - 2020
There is a large debate on the destabilization mechanism of emulsions. We present a simple technique using mechanical compression to destabilize oil-in-water emulsions. Upon compression of the emulsion, the continuous aqueous phase is squeezed out, while the dispersed oil phase progressively deforms from circular to honeycomb-like shapes. The films that separate the oil droplets are observed to thin and break at a critical oil/water ratio, leading to coalescence events. Electrostatic interactions and local droplet rearrangements do not determine film rupture. Instead, the destabilization occurs like an avalanche propagating through the system, starting at areas where the film thickness is smallest.
Density waves in shear-thickening suspensions
Laboratoire Matériaux Innovants pour l'Energie - Guillaume Ovarlez, Anh Vu Nguyen Le2, Wilbert J. Smit2, Abdoulaye Fall
Science Advances - 6 16 - DOI: 10.1126/sciadv.aay5589 - 2020
Shear thickening corresponds to an increase of the viscosity as a function of the shear rate. It is observed in many concentrated suspensions in nature and industry: water or oil saturated sediments, crystal-bearing magma, fresh concrete, silica suspensions, and cornstarch mixtures. Here, we reveal how shear-thickening suspensions flow, shedding light onto as yet non-understood complex dynamics reported in the literature. When shear thickening is important, we show the existence of density fluctuations that appear as periodic waves moving in the direction of flow and breaking azimuthal symmetry. They come with strong normal stress fluctuations of the same periodicity. The flow includes small areas of normal stresses of the order of tens of kilopascals and areas of normal stresses of the order of hundreds of pascals. These stress inhomogeneities could play an important role in the damage caused by thickening fluids in the industry.
Shear thickening in dense non-Brownian suspensions: Viscous to inertial transition
Laboratoire Matériaux Innovants pour l'Energie - Y. Madraki, A. Oakley, A. Nguyen Le, A. Colin, G. Ovarlez, and S. Hormozi
Journal of Rheology - 64 27 - doi.org/10.1122/1.5129680 - 2020
We present an experimental study on the viscous to inertial mode of shear thickening in dense non-Brownian suspensions. We design a model suspension consisting of monosized spherical particles within a Newtonian suspending fluid. We develop a protocol for the rheological characterization of dense suspensions using the conventional rheometry technique. Our results provide constitutive laws for suspensions with solid volume fractions close to jamming when both viscous and inertial effects at the particle scale are present. We perform atomic force microscopy to measure forces between the particles immersed in the suspending fluid and show that our system of study corresponds to the frictionless regime of dense suspensions in which viscous and collisional forces dissipate the energy. Finally, we show that the proposed empirical constitutive laws, when approaching jamming, predict the dynamics of dense suspensions in a transient boundary driven flow.
Impact of the Wetting Length on Flexible Blade Spreading
Laboratoire Matériaux Innovants pour l'Energie - Marion Krapez, Anaïs Gauthier, Hamid Kellay, Jean-Baptiste Boitte, Odile Aubrun, Jean-François Joanny, and Annie Colin
Phys. Rev. Lett. - 125 254506 - DOI:https://doi.org/10.1103 - 2020
We study the spreading of a Newtonian fluid by a deformable blade, a common industrial problem, characteristic of elastohydrodynamic situations. Here, we consider the case of a finite reservoir of liquid, emptying as the liquid is spread. We evidence the role of a central variable: the wetting length , which sets a boundary between the wet and dry parts of the blade. We show that the deposited film thickness
depends quadratically with. We study this problem experimentally and numerically by integration of the elastohydrodynamic equations, and finally propose a scaling law model to explain how influences the spreading dynamics.
A new pressure sensor array for local normal stress measurement in complex fluids
Laboratoire Matériaux Innovants pour l'Energie - Gauthier Anaïs, Mickael Pruvost, Gamache Olivier, Annie Colin
- - https://www.researchgate.net/publication/344603305 - 2020
A new pressure sensor array, positioned on the bottom plate of a standard torsional rheometer is presented. It is built from a unique piezo-capacitive polymeric foam, and consists of twenty-five capacitive pressure sensors (of surface 4.5$\times$4.5 mm$^2$ each) built together in a 5$\times$5 regular array. The sensor array is used to obtain a local mapping of the normal stresses in complex fluids, which dramatically extends the capability of the rheometer. We demonstrate this with three examples. First, the pressure profile is reconstructed in a polymer solution, which enable the simultaneous measurement of the first and the second normal stress differences $N_1$ and $N_2$, with a precision of 2 Pa. In a second part, we show that negative normal stresses can also be detected. Finally, we focus on the normal stress fluctuations that extend both spatially and temporally ina shear-thickening suspension of cornstarch particles. We evidence the presence of local a unique heterogeneity rotating very regularly. In addition to their low-cost and high versatility, the sensors show here their potential to finely characterize the normal stresses in viscosimetric flows
Microfluidics Mediated Production of Foams for Biomedical Applications
Laboratoire Microfluidique MEMS et nanostructures - Ilham Maimouni Cesare M. Cejas ,Janine Cossy ,Patrick Tabeling and Maria Russo
Micromachines - 11(1) 83 - doi.org/10.3390/mi11010083 - 2020
Within the last decade, there has been increasing interest in liquid and solid foams for several industrial uses. In the biomedical field, liquid foams can be used as delivery systems for dermatological treatments, for example, whereas solid foams are frequently used as scaffolds for tissue engineering and drug screening. Most of the foam functionalities are largely correlated to their mechanical properties and their structure, especially bubble/pore size, shape, and interconnectivity. However, the majority of conventional foaming fabrication techniques lack pore size control which can induce important inhomogeneities in the foams and subsequently decrease their performance. In this perspective, new advanced technologies have been introduced, such as microfluidics, which offers a highly controlled production, allowing for design customization of both liquid foams and solid foams obtained through liquid-templating. This short review explores both the fabrication and the characterization of foams, with a focus on solid polymer foams, and sheds the light on how microfluidics can overcome some existing limitations, playing a crucial role in their production for biomedical applications, especially as scaffolds in tissue engineering.

638 publications.