scholarly journals Microscopic precursors of failure in soft matter

Soft Matter ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 82-93 ◽  
Author(s):  
Luca Cipelletti ◽  
Kirsten Martens ◽  
Laurence Ramos
Keyword(s):  
Soft Matter ◽  
Mechanical Load ◽  
Delayed Failure ◽  
Soft Solids ◽  
Gravitational Stress

In analogy to a Dali-style clock that suddenly breaks under gravitational stress, soft matter under a mechanical load may exhibit delayed failure. We discuss recent works unveiling microscopic precursors of failure in amorphous soft solids.

scholarly journals Contact lines on stretched soft solids: modelling anisotropic surface stresses

2021 ◽  
Vol 477 (2245) ◽  
pp. 20200673
Author(s):  
Stefanie Heyden ◽  
Nicolas Bain ◽  
Qin Xu ◽  
Robert W. Style ◽  
Eric R. Dufresne
Keyword(s):  
Soft Matter ◽  
Liquid Droplet ◽  
Substrate Surface ◽  
Contact Lines ◽  
Soft Substrate ◽  
Soft Solids ◽  
Anisotropic Surface ◽  
Surface Profiles ◽  
Free Parameters ◽  
Lamé Coefficients

We present fully analytical solutions for the deformation of a stretched soft substrate due to the static wetting of a large liquid droplet, and compare our solutions to recently published experiments (Xu et al. 2018 Soft Matter 14, 916–920 (doi:10.1039/C7SM02431B)). Following a Green’s function approach, we extend the surface-stress regularized Flamant–Cerruti problem to account for uniaxial pre-strains of the substrate. Surface profiles, including the heights and opening angles of wetting ridges, are provided for linearized and finite kinematics. We fit experimental wetting ridge shapes as a function of applied strain using two free parameters, the surface Lamé coefficients. In comparison with experiments, we find that observed opening angles are more accurately captured using finite kinematics, especially with increasing levels of applied pre-strain. These fits qualitatively agree with the results of Xu et al ., but revise values of the surface elastic constants.

scholarly journals Faraday waves in soft elastic solids

2020 ◽  
Vol 476 (2241) ◽  
pp. 20200129
Author(s):  
Giulia Bevilacqua ◽  
Xingchen Shao ◽  
John R. Saylor ◽  
Joshua B. Bostwick ◽  
Pasquale Ciarletta
Keyword(s):  
Soft Matter ◽  
Theoretical Explanation ◽  
Subharmonic Resonance ◽  
Viscous Fluids ◽  
Faraday Waves ◽  
Elastic Solids ◽  
Soft Solids ◽  
Elastic Bodies ◽  
Faraday Instability ◽  
Elastic Slab

Recent experiments have observed the emergence of standing waves at the free surface of elastic bodies attached to a rigid oscillating substrate and subjected to critical values of forcing frequency and amplitude. This phenomenon, known as Faraday instability, is now well understood for viscous fluids but surprisingly eluded any theoretical explanation for soft solids. Here, we characterize Faraday waves in soft incompressible slabs using the Floquet theory to study the onset of harmonic and subharmonic resonance eigenmodes. We consider a ground state corresponding to a finite homogeneous deformation of the elastic slab. We transform the incremental boundary value problem into an algebraic eigenvalue problem characterized by the three dimensionless parameters, that characterize the interplay of gravity, capillary and elastic waves. Remarkably, we found that Faraday instability in soft solids is characterized by a harmonic resonance in the physical range of the material parameters. This seminal result is in contrast to the subharmonic resonance that is known to characterize viscous fluids, and opens the path for using Faraday waves for a precise and robust experimental method that is able to distinguish solid-like from fluid-like responses of soft matter at different scales.

scholarly journals Deformation of Microchannels Embedded in an Elastic Medium

2018 ◽  
Vol 85 (10) ◽  
Author(s):  
Vivek Ramachandran ◽  
Carmel Majidi
Keyword(s):  
Elastic Medium ◽  
Soft Matter ◽  
Numerical Solutions ◽  
Mechanical Load ◽  
Applied Pressure ◽  
Channel Cross Section ◽  
Gauge Factor ◽  
Microfluidic Channels ◽  
Linear Superposition ◽  
Cross Sectional

The deformation of microfluidic channels in a soft elastic medium has a central role in the operation of lab-on-a-chip devices, fluidic soft robots, liquid metal (LM) electronics, and other emerging soft-matter technologies. Understanding the influence of mechanical load on changes in channel cross section is essential for designing systems that either avoid channel collapse or exploit such collapse to control fluid flow and connectivity. In this paper, we examine the deformation of microchannel cross sections under far-field compressive stress and derive a “gauge factor” that relates externally applied pressure with change in cross-sectional area. We treat the surrounding elastomer as a Hookean solid and use two-dimensional plane strain elasticity, which has previously been shown to predict microchannel deformations that are in good agreement with experimental measurements. Numerical solutions to the governing Lamé (Navier) equations are found to match both the analytic solutions obtained from a complex stress function and closed-form algebraic approximations based on linear superposition. The application of this theory to soft microfluidics is demonstrated for several representative channel geometries.

Allosteric regulation of GPCR Rhodopsin by soft matter

2020 ◽  
Author(s):  
Nipuna Weerasinghe ◽  
Steven Fried ◽  
Anna Eitel ◽  
Andrey Struts ◽  
Suchithranga Perera ◽  
...  
Keyword(s):  
Soft Matter ◽  
Allosteric Regulation

Experimentally Applied Mechanical Load to the Human Knee Systematically Affects the Morphology of Articular Cartilage

2018 ◽  
Author(s):  
Grischa Bratke ◽  
Steffen Willwacher ◽  
David Maintz ◽  
Gert-Peter Brüggemann
Keyword(s):  
Articular Cartilage ◽  
Mechanical Load ◽  
Human Knee

Natural Killer Cell Inspired AIE Nanoterminator for Blood-Brain-Barrier Crossing via Tight-Junction Modulation and NIR-II Gliomas Theranostics

2020 ◽  
Author(s):  
Guanjun Deng ◽  
Xinghua Peng ◽  
Zhihong Sun ◽  
Wei Zheng ◽  
Jia Yu ◽  
...  
Keyword(s):  
Natural Killer Cell ◽  
Natural Killer ◽  
Intracellular Signaling ◽  
Soft Matter ◽  
Tumor Imaging ◽  
Nk Cell ◽  
Killer Cell ◽  
Light Illumination ◽  
Blood Brain ◽  
Intracellular Signaling Cascade

Nature has always inspired robotic designs and concepts. It is conceivable that biomimic nanorobots will soon play a prominent role in medicine. In this paper, we developed a natural killer cell-mimic AIE nanoterminator (NK@AIEdots) by coating natural kill cell membrane on the AIE-active polymeric endoskeleton, PBPTV, a highly bright NIR-II AIE-active conjugated polymer. Owning to the AIE and soft-matter characteristics of PBPTV, as-prepared nanoterminator maintained the superior NIR-II brightness (quantum yield ~8%) and good biocompatibility. Besides, they could serve as tight junctions (TJs) modulator to trigger an intracellular signaling cascade, causing TJs disruption and actin cytoskeleton reorganization to form intercellular “green channel” to help themselves crossing Blood-Brain Barriers (BBB) silently. Furthermore, they could initiatively accumulate to glioblastoma cells in the complex brain matrix for high-contrast and through-skull tumor imaging. The tumor growth was also greatly inhibited by these nanoterminator under the NIR light illumination. As far as we known, The QY of PBPTV is the highest among the existing NIR-II luminescent conjugated polymers. Besides, the NK-cell biomimetic nanorobots will open new avenue for BBB-crossing delivery.

Sensitive Mechanocontrolled Luminescence in Cross-Linked Polymer Films

2019 ◽  
Author(s):  
Ayumu Karimata ◽  
Pradnya Patil ◽  
Eugene Khaskin ◽  
Sébastien Lapointe ◽  
robert fayzullin ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Polymer Films ◽  
Soft Matter ◽  
Small Strain ◽  
Visual Methods ◽  
Photoluminescence Intensity ◽  
Stimuli Responsive ◽  
Responsive Materials ◽  
Highly Sensitive ◽  
Mechanical Stretching

Direct translation of mechanical force into changes in chemical behavior on a molecular level has important implication not only for the fundamental understanding of mechanochemical processes, but also for the development of new stimuli-responsive materials. In particular, detection of mechanical stress in polymers via non-destructive methods is important in order to prevent material failure and to study the mechanical properties of soft matter. Herein, we report that highly sensitive changes in photoluminescence intensity can be observed in response to the mechanical stretching of cross-linked polymer films when using stable, (pyridinophane)Cu-based dynamic mechanophores. Upon stretching, the luminescence intensity increases in a fast and reversible manner even at small strain (< 50%) and applied stress (< 0.1 MPa) values. Such sensitivity is unprecedented when compared to previously reported systems based on organic mechanophores. The system also allows for the detection of weak mechanical stress by spectroscopic measurements or by direct visual methods.<br>

Sign in / Sign up

Export Citation Format

Share Document