Contactless rheology of finite-size air-water interfaces

Contactless Rheology of Soft Gels over a Broad Frequency Range

We report contactless measurements of the viscoelastic rheological properties of soft gels. The experiments are performed using a colloidal-probe Atomic Force Microscope (AFM) in a liquid environment and in dynamic mode. The mechanical response is measured as a function of the liquid gap thickness for different oscillation frequencies. Our measurements reveal an elastohydrodynamic (EHD) coupling between the flow induced by the probe oscillation and the viscoelastic deformation of the gels. The data are quantitatively described by a viscoelastic lubrication model. The frequency-dependent storag…

Mechanical response of a thick poroelastic gel in contactless colloidal-probe rheology

When a rigid object approaches a soft material in a viscous fluid, hydrodynamic stresses arise in the lubricated contact region and deform the soft material. The elastic deformation modifies in turn the flow, hence generating a soft-lubrication coupling. Moreover, soft elastomers and gels are often porous. These materials may be filled with solvent or uncrosslinked polymer chains, and might be permeable to the surrounding fluid, which complexifies further the description. Here, we derive the point-force response of a semi-infinite and permeable poroelastic substrate. Then, we use this fundamen…

Contactless Interfacial Rheology: Probing Shear at Liquid-Liquid Interfaces without an Interfacial Geometry via Fluorescence Microscopy

Interfacial rheology is important for understanding properties such as Pickering emulsion or foam stability. Currently, the response is measured using a probe directly attached to the interface. This can both disturb the interface and is coupled to flow in the bulk phase, limiting its sensitivity. We have developed a contactless interfacial method to perform interfacial shear rheology on liquid/liquid interfaces with no tool attached directly to the interface. This is achieved by shearing one of the liquid phases and measuring the interfacial response via confocal microscopy. Using this method…

与脂质界面相关的二维F-actin网络的流变学

Rheology of two-dimensional F-actin networks associated with a lipid interface

我们报告的表面流变学的交联F-肌动蛋白网络与脂质单层在空气-水界面的朗缪尔单层。使用库埃特池进行流变测量。这些数据表明，该网络具有有限的弹性模量，其作为交联浓度的函数而增长。我们还注意到，在稳态流动下，系统表现为幂律流体，其中有效粘度随施加的剪切而减小。

镧系结合肽表面活性剂在空气-水界面的界面流变学

Interfacial Rheology of Lanthanide Binding Peptide Surfactants at the Air-Water Interface

研究肽表面活性剂在空气-水界面捕获稀土元素的流变学行为，发现配位球外的阴离子配体会导致非特异性阳离子招募和界面凝胶化，提出了避免此类配体以保持界面选择性的设计要求。

On the rheology of pulmonary surfactant: effects of concentration and consequences for the surfactant replacement therapy

The role of pulmonary surfactant is to reduce the surface tension in the lungs and to facilitate breathing. Surfactant replacement therapy (SRT) aims at bringing a substitute by instillation into the airways, a technique that has proven to be efficient and lifesaving for preterm infants. Adapting this therapy to adults requires to scale the administered dose to the patient body weight and to in-crease the lipid concentration, whilst maintaining its surface and flow properties similar. Here, we exploit a magnetic wire-based microrheology technique to measure the viscosity of the exogenous pulmo…