Tuning Molecular Adhesion via Material Anisotropy

Zhang, Wenliang; Lin, Yuan; Qian, Jin; Chen, Weiqiu; Gao, Huajian

doi:10.1002/adfm.201300069

Cited by 28 publications

(21 citation statements)

References 52 publications

(69 reference statements)

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“…Live cells were shown to volumetrically shrink or swell via cross-membrane ion transport upon applied mechanical pressure (Hui et al, 2014). These results highlight the distinct advantage of involving biologically based materials in DE actuation and energy harvesting, and open a new avenue to build DE-made soft machines with tunable mechanical, chemical as well as electrical properties to generate active force/ motion at the (sub)cellular scale for potential applications in biomaterials and biointerfaces Zhang et al, 2013).…”

Section: Concluding Remarks and Outlookmentioning

confidence: 90%

Mechanics of dielectric elastomers: materials, structures, and devices

Qian

2016

JZUS-A

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Dielectric elastomers (DEs) respond to applied electric voltage with a surprisingly large deformation, showing a promising capability to generate actuation in mimicking natural muscles. A theoretical foundation of the mechanics of DEs is of crucial importance in designing DE-based structures and devices. In this review, we survey some recent theoretical and numerical efforts in exploring several aspects of electroactive materials, with emphases on the governing equations of electromechanical coupling, constitutive laws, viscoelastic behaviors, electromechanical instability as well as actuation applications. An overview of analytical models is provided based on the representative approach of non-equilibrium thermodynamics, with computational analyses being required in more generalized situations such as irregular shape, complex configuration, and time-dependent deformation. Theoretical efforts have been devoted to enhancing the working limits of DE actuators by avoiding electromechanical instability as well as electric breakdown, and pre-strains are shown to effectively avoid the two failure modes. These studies lay a solid foundation to facilitate the use of DE materials, structures, and devices in a wide range of applications such as biomedical devices, adaptive systems, robotics, energy harvesting, etc.

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Section: Concluding Remarks and Outlookmentioning

confidence: 90%

Mechanics of dielectric elastomers: materials, structures, and devices

Qian

2016

JZUS-A

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“…Many biological materials are transversely isotropic [5,6]. Following the notations in Bower [25] as shown in figure 6a, the elastic constants include the directional modulus in p and t directions, E p and E t , in-plane and out-of-plane Poisson's ratios, n p and n tp , and shear modulus m t .…”

Section: Anisotropic Elastic Substrate With Transverse Isotropymentioning

confidence: 99%

“…A representative set of parameters is given in table 1 as Material (B) [6]. Keeping all other elastic constants the same rsif.royalsocietypublishing.org J. R. Soc.…”

Section: Anisotropic Elastic Substrate With Transverse Isotropymentioning

confidence: 99%

Non-uniform breaking of molecular bonds, peripheral morphology and releasable adhesion by elastic anisotropy in bio-adhesive contacts

Liu

Gao

2015

J. R. Soc. Interface.

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Biological adhesive contacts are usually of hierarchical structures, such as the clustering of hundreds of sub-micrometre spatulae on keratinous hairs of gecko feet, or the clustering of molecular bonds into focal contacts in cell adhesion. When separating these interfaces, releasable adhesion can be accomplished by asymmetric alignment of the lowest scale discrete bonds (such as the inclined spatula that leads to different peeling force when loading in different directions) or by elastic anisotropy. However, only two-dimensional contact has been analysed for the latter method (Chen & Gao 2007 J. Mech. Phys. Solids 55, 1001-1015 (doi:10.1016/j.jmps.2006.10.008)). Important questions such as the three-dimensional contact morphology, the maximum to minimum pull-off force ratio and the tunability of releasable adhesion cannot be answered. In this work, we developed a three-dimensional cohesive interface model with fictitious viscosity that is capable of simulating the de-adhesion instability and the peripheral morphology before and after the onset of instability. The two-dimensional prediction is found to significantly overestimate the maximum to minimum pull-off force ratio. Based on an interface fracture mechanics analysis, we conclude that (i) the maximum and minimum pull-off forces correspond to the largest and smallest contact stiffness, i.e. 'stiff-adhere and compliant-release', (ii) the fracture toughness is sensitive to the crack morphology and the initial contact shape can be designed to attain a significantly higher maximum-to-minimum pull-off force ratio than a circular contact, and (iii) since the adhesion is accomplished by clustering of discrete bonds or called bridged crack in terms of fracture mechanics terminology, the above conclusions can only be achieved when the bridging zone is significantly smaller than the contact size. This adhesion-fracture analogy study leads to mechanistic predictions that can be readily used to design biomimetics and releasable adhesives.

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“…While biomechanics gets into the cell or molecular level (Janmey and McCulloch, 2007;Zhang et al, 2013), ongoing research interest has gradually veered towards biological functions and physiopathological consequences resulting from mechanical properties or responses of biological systems. This leads to a new emerging field of science, i.e., mechanobiology, which is also at the interface of biology and mechanics (engineering) but with more emphasis being placed on the biological side (Stoltz and Wang, 2002).…”

Section: Biomechanics Evolves Into Mechanobiologymentioning

confidence: 99%

The renaissance of continuum mechanics

Chen

2014

J. Zheijang Univ.-Sci.

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Continuum mechanics, just as the name implies, deals with the mechanics problems of all continua, whose physical (or mechanical) properties are assumed to vary continuously in the spaces they occupy. Continuum mechanics may be seen as the symbol of modern mechanics, which differs greatly from current physics, the two often being mixed up by people and even scientists. In this short paper, I will first try to give an illustration on the differences between (modern) mechanics and physics, in my personal view, and then focus on some important current research activities in continuum mechanics, attempting to identify its path to the near future. We can see that continuum mechanics, while having a dominating impact on engineering design in the 20th century, also plays a pivotal role in modern science, and is much closer to physics, chemistry, biology, etc. than ever before.

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Tuning Molecular Adhesion via Material Anisotropy

Cited by 28 publications

References 52 publications

Mechanics of dielectric elastomers: materials, structures, and devices

Mechanics of dielectric elastomers: materials, structures, and devices

Non-uniform breaking of molecular bonds, peripheral morphology and releasable adhesion by elastic anisotropy in bio-adhesive contacts

The renaissance of continuum mechanics

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