Abstract Flexible low-pressure sensors ( <10 kPa) are required in areas as diverse blood-pressure monitoring, human–computer interactions, robotics, and object detection. For applications, it is essential that these combine flexibility, high sensitivity, robustness, low production costs. Previous works involve surface micro-patterning, electronic amplification (OFET), hydrogels. However, solutions limited they complex processes, large bias voltages, energy consumption, or sensitive to...

Graphene oxide (GO), the main precursor of graphene-based materials made by solution processing, is known to be very stiff. Indeed, it has a Young's modulus comparable steel, on order 300 GPa. Despite its high stiffness, we show here that GO superflexible. We quantitatively measure bending rigidity characterizing flattening thermal undulations in response shear forces solution. Characterizations are performed combination synchrotron X-ray diffraction at small angles and situ rheology...

Graphene flakes with giant shape anisotropy are extensively used to establish connectedness electrical percolation in various heterogeneous systems. However, the behaviour of graphene has been recently predicted be far more complicated than generally anticipated on basis excluded volume arguments. Here we confirm experimentally that self-assemble into nematic liquid crystals below onset percolation. The competition and crystal transition provides a new route towards high-k materials. Indeed,...

We study the flow of suspensions non-Brownian particles dispersed in a Newtonian solvent.

In this work, a viscosimeter implemented on microfluidic chip is presented. The physical principle of system to use laminar parallel flows in channel. fluid be studied side by with reference known viscosity. By using optical microscopy, the shape interface between both fluids can determined. Knowing flow rates two liquids and geometrical features channel, mean shear rate sustained its viscosity thus computed. Accurate precise measurements as function made less than 300 microL fluid. Several...

Abstract In this study, the effect of flow electrolyte on an electrolysis cell and a zinc is investigated. The gain energy brought by discussed compared to viscous losses in cells. We point out that balance between gained electrical power loss positive only if hydrodynamic resistance circuit correctly designed further comment economical viability whole process. A model studied phenomena proposed last section. This analytical captures dynamics process, gives optimal flowing conditions limits...

We report some time-dependent behavior of lyotropic lamellar phase under shear flow. At fixed stress, near a layering instability, the system presents an oscillating rate. build up new stress versus rate diagram that includes temporal behavior. This is made two distinct branches stationary states which correspond, respectively, to disordered and ordered multilamellar vesicle phases. When increasing prior transition structural state, sustained oscillations viscosity are recorded. They...

We explore the question of surface boundary conditions for flow a dense emulsion. make use microlithographic tools to create surfaces with well controlled roughness patterns and measure using dynamic confocal microscopy both slip velocity shear rate close wall, which we relate notion fluidization. Both slippage wall fluidization depend non-monotonously on roughness. interpret this behavior within simple model in terms building stratified layer activation plastic events by

Drying graphene oxide (GO) films are subject to extensive wrinkling, which largely affects their final properties. Wrinkles were shown be suitable in biotechnological applications; however, they negatively affect the electronic properties of films. Here, we report on wrinkle tuning and patterning GO under stress-controlled conditions during drying. flakes assemble at an air–solvent interface; assembly forms a skin surface may bend due volume shrinkage while We applied modification...

High electromechanical coupling is critical to perform effective conversion between mechanical and electrical energy for various applications of electrostrictive polymers. Herein, a giant electrostriction effect reported in liquid crystalline graphene-doped dielectric elastomers. The materials are formulated by phase-transfer method which allows the solubilization graphenic monolayers nonpolar solvents. Dielectric spectroscopy combined with tensile test devices measure true coefficients...

Abstract Coating surfaces with different fluids is prone to instability producing inhomogeneous films and patterns. The contact line between the coating fluid surface be coated host instabilities, limiting use of a variety techniques. Here we take advantage receding towards cusp droplet formation produce linear patterns variable spacings. We stabilize cusps by using polymer solutions that inhibit this secondary give rise long slender cylindrical filaments. vary speed deposition change...

Abstract Microenergy storage devices are appealing and highly demanded for diverse miniaturized electronic devices, ranging from microelectromechanical system, robotics, to sensing microsystems wearable electronics. However, making high‐energy microcapacitors with currently available printing technologies remains challenging. Herein, the possibility use latex polyvinylidene fluoride (PVDF) as aqueous ink dielectric capacitors at microscale is shown. The properties of printed can be optimized...

We describe an optical fiber based interferometer to measure velocity profiles in sheared complex fluids using Dynamic Light Scattering (DLS). After a review of the theoretical problem DLS under shear, detailed description setup is given. outline various experimental difficulties induced by refraction when Couette cell. also show that homodyne not well suited quantitative narrow-gap geometries. On other hand, heterodyne technique allows us determine field inside gap All technical features...

Near-percolated CNT-polymer composites are promising high-permittivity materials. The main challenge in the field consists of finding compromises that allow high permittivity and low losses frequency ranges interest. Using an emulsion approach optimizing size droplets curing procedure, we obtain unprecedented performances measure giant larger than 20,000 at 100 Hz along with a conductivity below 10(-4) S/m.

In this paper, we present a dynamic microfluidic tensiometer able to perform measurements over more than four decades and which is suitable for high throughput experimentations. This withstand hard conditions such as pressure, temperature, salinity, crude oil. It made of two coaxial capillaries in immiscible fluids are injected. Depending on the flow rate each phase, either droplets or jetting will be obtained. The transition between these regimes relies Rayleigh-Plateau instability. can...

Using an emulsion road and optimizing the dispersion process, we prepare polymer carbone nanotubes (CNT) reduced graphene oxide (rGO) composites. The introduction of conductive nanoparticles into matrices modifies electronic properties material. We show that these materials exhibit giant electrostriction coefficients in intermediate filler concentration (below 1 wt %). This makes them very promising for applications such as capacitive sensors actuators. In addition, values piezoresistivity...

We study experimentally and theoretically the thickness of coating obtained by pulling out a rod from reservoir yield-stress fluid. Opposite to Newtonian fluids, for fluid large enough yield stress is determined solely flow inside not meniscus. The field determines layer. observed increase nonlinearly with sizes reservoir. develop theoretical framework that describes this behavior allows us precisely predict thickness.

Rigid blade coating of glass plates by oil-in-water emulsions stabilized surfactants is studied. Complete surface coverage obtained only for speeds exceeding a threshold velocity dependent on the height between end and surface. Below this threshold, emulsion can be inverted in vicinity blade. The inversion dynamics deposition patterns induced phase are studied using microscope mounted set up. We show that these universal different volume fractions velocities. This as well destabilization...

Flows of suspensions can be blocked when the suspended particles are densely packed. This makes their formulation and transport challenging in industry. In this paper, we study impact vibrations on behavior dense granular prepared at a volume fraction above jamming but below particle assembly random close packing. Vibrations shown to have strong effect rheological properties tune transition from solidlike liquidlike behavior. We rough silica Newtonian fluid. absence vibrations, they...

In this work, we propose a new way to measure the viscosity of samples in microfluidic device.

We present electrostrictive materials with excellent properties for vibrational energy harvesting applications. The developed consist of a porous carbon black composite, which is processed using water-in-oil emulsions. In combination an insulating layer, the investigated structures exhibit high effective relative dielectric permittivity (up to 182 at 100 Hz) very low conductivity (down 2.53 10−8 S m−1). They can generate electrical in response mechanical vibrations power density 0.38 W m−3...

Abstract In the case of surfactant EOR, an optimum formulation has to be injected in reservoir. This so-called corresponds a minimum interfacial tension and maximum oil recovery may obtained with appropriate balance hydrophobic hydrophilic affinities surfactant. Salinity—scan tests are generally used screen phase behavior formulations before conducting time-consuming coreflood tests. The objective this study was develop high-throughput dynamic microfluidic tensiometer, aim studying phenomena...