scholarly journals Design of gecko-inspired fibrillar surfaces with strong attachment and easy-removal properties: a numerical analysis of peel-zone

2012 ◽  
Vol 9 (75) ◽  
pp. 2424-2436 ◽  
Author(s):  
Ming Zhou ◽  
Noshir Pesika ◽  
Hongbo Zeng ◽  
Jin Wan ◽  
Xiangjun Zhang ◽  
...  
Keyword(s):  
Peel Strength ◽  
Geometrical Parameters ◽  
Adhesion Forces ◽  
Rigid Substrate ◽  
Reversible Adhesion ◽  
Fundamental Understanding ◽  
Strong Adhesion ◽  
Strong Attachment ◽  
Peeling Off ◽  
Zone Deformation

Despite successful fabrication of gecko-inspired fibrillar surfaces with strong adhesion forces, how to achieve an easy-removal property becomes a major concern that may restrict the wide applications of these bio-inspired surfaces. Research on how geckos detach rapidly has inspired the design of novel adhesive surfaces with strong and reversible adhesion capabilities, which relies on further fundamental understanding of the peeling mechanisms. Recent studies showed that the peel-zone plays an important role in the peeling off of adhesive tapes or fibrillar surfaces. In this study, a numerical method was developed to evaluate peel-zone deformation and the resulting mechanical behaviour due to the deformations of fibrillar surfaces detaching from a smooth rigid substrate. The effect of the geometrical parameters of pillars and the stiffness of backing layer on the peel-zone and peel strength, and the strong attachment and easy-removal properties have been analysed to establish a design map for bio-inspired fibrillar surfaces, which shows that the optimized strong attachment and easy-removal properties can vary by over three orders of magnitude. The adhesion and peeling design map established provides new insights into the design and development of novel gecko-inspired fibrillar surfaces.

scholarly journals Carbohydrate–carbohydrate interaction provides adhesion force and specificity for cellular recognition

2004 ◽  
Vol 165 (4) ◽  
pp. 529-537 ◽  
Author(s):  
Iwona Bucior ◽  
Simon Scheuring ◽  
Andreas Engel ◽  
Max M. Burger
Keyword(s):  
Adhesion Force ◽  
Species Specificity ◽  
Live Cells ◽  
Sponge Cell ◽  
Cell Recognition ◽  
Adhesion Forces ◽  
Cellular Recognition ◽  
Strong Adhesion ◽  
Species Specific ◽  
Cell Cell

The adhesion force and specificity in the first experimental evidence for cell–cell recognition in the animal kingdom were assigned to marine sponge cell surface proteoglycans. However, the question whether the specificity resided in a protein or carbohydrate moiety could not yet be resolved. Here, the strength and species specificity of cell–cell recognition could be assigned to a direct carbohydrate–carbohydrate interaction. Atomic force microscopy measurements revealed equally strong adhesion forces between glycan molecules (190–310 piconewtons) as between proteins in antibody–antigen interactions (244 piconewtons). Quantitative measurements of adhesion forces between glycans from identical species versus glycans from different species confirmed the species specificity of the interaction. Glycan-coated beads aggregated according to their species of origin, i.e., the same way as live sponge cells did. Live cells also demonstrated species selective binding to glycans coated on surfaces. These findings confirm for the first time the existence of relatively strong and species-specific recognition between surface glycans, a process that may have significant implications in cellular recognition.

scholarly journals Sliding-induced non-uniform pre-tension governs robust and reversible adhesion: a revisit of adhesion mechanisms of geckos

2011 ◽  
Vol 9 (67) ◽  
pp. 283-291 ◽  
Author(s):  
Q. H. Cheng ◽  
B. Chen ◽  
H. J. Gao ◽  
Y. W. Zhang
Keyword(s):  
Computational Modelling ◽  
Simulation Approach ◽  
Linear Distribution ◽  
Sliding Motion ◽  
Reversible Adhesion ◽  
Vertical Walls ◽  
Strong Attachment ◽  
Pulling Force ◽  
Complete Detachment ◽  
Key Steps

Several mechanisms have been proposed in the literature to explain the robust attachment and rapid, controllable detachment of geckos' feet on vertical walls or ceilings, yet, it is still debatable, which one is ultimately responsible for geckos' extraordinary capabilities for robust and reversible adhesion. In this paper, we re-examine some of the key movements of geckos' spatula pads and seta hairs during attachment and detachment, and propose a sequence of simple mechanical steps that would lead to the extraordinary properties of geckos observed in experiments. The central subject under study here is a linear distribution of pre-tension along the spatula pad induced by its sliding motion with respect to a surface. The resulting pre-tension, together with a control of setae's pulling force and angle, not only allows for robust and strong attachment, but also enables rapid and controllable detachment. We perform computational modelling and simulations to validate the following key steps of geckos' adhesion: (i) creation of a linear distribution of pre-tension in spatula through sliding, (ii) operation of an instability envelope controlled by setae's pulling force and angle, (iii) triggering of an adhesion instability leading to partial decohesion along the interface, and (iv) complete detachment of spatula through post-instability peeling. The present work not only reveals novel insights into the adhesion mechanism of geckos, but also develops a powerful numerical simulation approach as well as additional guidelines for bioinspired materials and devices.

Bonding of Butyl and Nitrile Rubber by in situ Copolymer Formation

1989 ◽  
Vol 62 (2) ◽  
pp. 367-385 ◽  
Author(s):  
M. H. Chung ◽  
G. R. Hamed
Keyword(s):  
Molecular Weight ◽  
Peel Strength ◽  
Low Molecular Weight ◽  
Temperature Dependent ◽  
Wlf Equation ◽  
Test Speed ◽  
Strong Adhesion ◽  
Peel Adhesion ◽  
Dependent Failure

Abstract We summarize and conclude the following: 1. The T-peel adhesion between uncrosslinked layers of IIR and NBR is rate and temperature dependent. Failure is interfacial at low rates; bulk cohesive tearing of the rubber occurs at intermediate rates, while interfacial failure returns at high rates. 2. Adhesion data could be reduced to mastercurves with experimentally determined shift factors which were in reasonable agreement with those calculated from the universal WLF equation with a Tg=−69°C. 3. At the lowest test rates, peel specimens containing in situ-formed copolymer had lower strength than those without the copolymer. This is probably due to the easy slippage of the segments of the low-molecular-weight copolymer in this regime. 4. At intermediate rates, in situ copolymer had no effect on peel strength; specimens failed by bulk cohesive tearing of rubber, whether or not the copolymer was present. 5. At high rates, peel specimens containing the copolymer exhibited improved strengths. The behavior is consistent with previous results on the autohesion of elastomers. Interdiffused chains of relatively low molecular weight are only capable of providing strong adhesion when the test speed is sufficiently rapid.

scholarly journals Robust scalable reversible strong adhesion by gecko-inspired composite design

Friction ◽  
2021 ◽  
Author(s):  
Xiaosong Li ◽  
Pengpeng Bai ◽  
Xinxin Li ◽  
Lvzhou Li ◽  
Yuanzhe Li ◽  
...  
Keyword(s):  
Flexible Electronics ◽  
Natural State ◽  
Large Area ◽  
High Adhesion ◽  
Wide Range ◽  
Grasping And Manipulation ◽  
Strong Adhesion ◽  
Strong Attachment ◽  
And Control ◽  
Intelligent Robotics

AbstractBio-inspired reversible adhesion has significant potential in many fields requiring flexible grasping and manipulation, such as precision manufacturing, flexible electronics, and intelligent robotics. Despite extensive efforts for adhesive synthesis with a high adhesion strength at the interface, an effective strategy to actively tune the adhesion capacity between a strong attachment and an easy detachment spanning a wide range of scales has been lagged. Herein, we report a novel soft-hard-soft sandwiched composite design to achieve a stable, repeatable, and reversible strong adhesion with an easily scalable performance for a large area ranging from ∼1.5 to 150 cm2 and a high load ranging from ∼20 to 700 N. Theoretical studies indicate that this design can enhance the uniform loading for attachment by restraining the lateral shrinkage in the natural state, while facilitate a flexible peeling for detachment by causing stress concentration in the bending state, yielding an adhesion switching ratio of ∼54 and a switching time of less than ∼0.2 s. This design is further integrated into versatile grippers, climbing robots, and human climbing grippers, demonstrating its robust scalability for a reversible strong adhesion. This biomimetic design bridges microscopic interfacial interactions with macroscopic controllable applications, providing a universal and feasible paradigm for adhesion design and control.

Hierarchical modelling of attachment and detachment mechanisms of gecko toe adhesion

2008 ◽  
Vol 464 (2094) ◽  
pp. 1639-1652 ◽  
Author(s):  
B Chen ◽  
P.D Wu ◽  
H Gao
Keyword(s):  
Body Weight ◽  
Surface Area ◽  
Process Zone ◽  
Adhesive Force ◽  
Adhesion Energy ◽  
Adhesion Forces ◽  
Hierarchical Modelling ◽  
Reversible Adhesion ◽  
Peeling Strength ◽  
Attachment Process

The mechanics of reversible adhesion of the gecko is investigated in terms of the attachment and detachment mechanisms of the hierarchical microstructures on its toe. At the bottom of the hierarchy, we show that a spatula pad of tiny thickness can be well absorbed onto a substrate with a large surface area and a highly constrained decohesion process zone, both of which are beneficial for robust attachment. With different peeling angles, the peeling strength of a spatula pad for attachment can be 10 times larger than that for detachment. At the intermediate level of hierarchy, we show that a seta can achieve a stress level similar to that in the spatula pad by uniformly distributing adhesion forces; as a consequence, the 10 times difference in the peel-off force of a single spatula pad for attachment and detachment is magnified up to a 100 times difference in adhesion energy at the level of seta. At the top of the hierarchy, the attachment process of a gecko toe is modelled as a pad under displacement-controlled pulling, leading to an adhesive force much larger than the gecko's body weight, while the associated detachment process is modelled as a pad under peeling, resulting in a negligible peel-off force. The present work reveals, in a more systematic way than previous studies in the literature, that the hierarchical microstructures on the gecko's toe can indeed provide the gecko with robust adhesion for attachment and reversible adhesion for easy detachment at the same time.

scholarly journals Adhesion energy can regulate vesicle fusion and stabilize partially fused states

2012 ◽  
Vol 9 (72) ◽  
pp. 1555-1567 ◽  
Author(s):  
Rong Long ◽  
Chung-Yuen Hui ◽  
Anand Jagota ◽  
Maria Bykhovskaia
Keyword(s):  
Metastable State ◽  
Synaptic Vesicles ◽  
Membrane Curvature ◽  
Fusion Process ◽  
Synaptic Membrane ◽  
Adhesion Forces ◽  
Molecular Adhesion ◽  
Strong Adhesion ◽  
Molecular Machinery ◽  
Molecular Components

Release of neurotransmitters from nerve terminals occurs by fusion of synaptic vesicles with the plasma membrane, and this process is highly regulated. Although major molecular components that control docking and fusion of vesicles to the synaptic membrane have been identified, the detailed mechanics of this process is not yet understood. We have developed a mathematical model that predicts how adhesion forces imposed by docking and fusion molecular machinery would affect the fusion process. We have computed the membrane stress that is produced by adhesion-driven vesicle bending and find that it is compressive. Further, our computations of the membrane curvature predict that strong adhesion can create a metastable state with a partially opened pore that would correspond to the ‘kiss and run’ release mode. Our model predicts that the larger the vesicle size, the more likely the metastable state with a transiently opened pore. These results contribute to understanding the mechanics of the fusion process, including possible clamping of the fusion by increasing molecular adhesion, and a balance between ‘kiss and run’ and full collapse fusion modes.

scholarly journals High-Speed Manipulation of Microobjects Using an Automated Two-Fingered Microhand for 3D Microassembly

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 534
Author(s):  
Eunhye Kim ◽  
Masaru Kojima ◽  
Yasushi Mae ◽  
Tatsuo Arai
Keyword(s):  
High Speed ◽  
Positional Error ◽  
Adhesion Forces ◽  
Nih3t3 Cells ◽  
Manipulation System ◽  
Strong Adhesion ◽  
3D Assembly ◽  
End Effectors ◽  
2D And 3D ◽  
Pick And Place Operation

To assemble microobjects including biological cells quickly and precisely, a fully automated pick-and-place operation is applied. In micromanipulation in liquid, the challenges include strong adhesion forces and high dynamic viscosity. To solve these problems, a reliable manipulation system and special releasing techniques are indispensable. A microhand having dexterous motion is utilized to grasp an object stably, and an automated stage transports the object quickly. To detach the object adhered to one of the end effectors, two releasing methods—local stream and a dynamic releasing—are utilized. A system using vision-based techniques for the recognition of two fingertips and an object, as well automated releasing methods, can increase the manipulation speed to faster than 800 ms/sphere with a 100% success rate (N = 100). To extend this manipulation technique, 2D and 3D assembly that manipulates several objects is attained by compensating the positional error. Finally, we succeed in assembling 80–120 µm of microbeads and spheroids integrated by NIH3T3 cells.

Effect of Presputtering on the Adhesion of Cu to Teflon

1987 ◽  
Vol 93 ◽  
Author(s):  
Chin-An Chang ◽  
K. C. Lin ◽  
J. E. E. Baglin ◽  
G. Coleman ◽  
J. Park
Keyword(s):  
Surface Morphology ◽  
Chemical Bonding ◽  
Peel Strength ◽  
Cu Films ◽  
Scotch Tape ◽  
Strong Adhesion

ABSTRACTAdhesion between Cu and Teflon has been greatly enhanced by a presputtering treatment of the Teflon prior to the deposition of Cu. Without such a treatment, the Cu-Teflon adhesion is weak, with a peel strength less than 1 gram/mm, and the Cu films can be easily peeled off using scotch tape. With the presputtering treatment, the adhesion rapidly increases, and reaches 50 grams/mm after 30 sec of sputtering. All the sputtered samples show strong adhesion, and the Cu films can only be scratched off forcefully using sharp tools. The presputtering treatment has changed the surface morphology of the Teflon and the deposited Cu layers, and also changes the chemical bonding between Cu and Teflon. The results are discussed to understand the mechanisms involved for the enhanced adhesion observed.

scholarly journals Direct Probing of the Surface Ultrastructure and Molecular Interactions of Dormant and Germinating Spores ofPhanerochaete chrysosporium

1999 ◽  
Vol 181 (17) ◽  
pp. 5350-5354 ◽  
Author(s):  
Yves F. Dufrêne ◽  
Christophe J. P. Boonaert ◽  
Patrick A. Gerin ◽  
Marcel Asther ◽  
Paul G. Rouxhet
Keyword(s):  
Molecular Interactions ◽  
Fungal Spores ◽  
Adhesion Forces ◽  
Distance Curve ◽  
Surface Ultrastructure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Strong Adhesion ◽  
High Resolution Images ◽  
Freeze Etching

ABSTRACT Atomic force microscopy (AFM) has been used to probe, under physiological conditions, the surface ultrastructure and molecular interactions of spores of the filamentous fungus Phanerochaete chrysosporium. High-resolution images revealed that the surface of dormant spores was uniformly covered with rodlets having a periodicity of 10 ± 1 nm, which is in agreement with earlier freeze-etching measurements. In contrast, germinating spores had a very smooth surface partially covered with rough granular structures. Force-distance curve measurements demonstrated that the changes in spore surface ultrastructure during germination are correlated with profound modifications of molecular interactions: while dormant spores showed no adhesion with the AFM probe, germinating spores exhibited strong adhesion forces, of 9 ± 2 nN magnitude. These forces are attributed to polysaccharide binding and suggested to be responsible for spore aggregation. This study represents the first direct characterization of the surface ultrastructure and molecular interactions of living fungal spores at the nanometer scale and offers new prospects for mapping microbial cell surface properties under native conditions.

Adhesion of viscoelastic materials to rigid substrates

1969 ◽  
Vol 310 (1502) ◽  
pp. 433-448 ◽  
Keyword(s):  
Sharp Decrease ◽  
Peel Strength ◽  
Adhesive Failure ◽  
Interfacial Bond ◽  
Rigid Substrate ◽  
Interfacial Bond Strength ◽  
Approximate Relation ◽  
Strain Behaviour ◽  
Wide Range ◽  
Mode Of Failure

Measurements have been made of the forces required to peel a thin layer of a model visco-elastic adhesive off a rigid substrate. Over a wide range of temperature and rate of peel the results were found to yield a single master relation in terms of peel rate when reduced to a reference temperature by means of the Williams, Landel & Ferry rate–temperature equivalence for viscous materials. The relations obtained were complex, however, with two main features: a cohesive–adhesive failure transition at low rates and a sharp decrease in peel strength at high rates. The first effect is shown to be due to a change in the deformation process in the adhesive, from a liquid-like to a rubber-like response. An approximate relation between peel strength and the tensile stress–strain behaviour of the adhesive is developed in terms of a single empirically-determined parameter, the interfacial bond strength. Values of this parameter are deduced for several substrates. Measurements of peeling under hydrostatic pressure showed that cavitation of the adhesive did not occur in these experiments. The second effect is shown to be due to the transition from a rubber-like to a glass-like response of the adhesive. It is also shown to depend on the way in which separation is effected. Some general principles governing the mode of failure and the development of maximum peel strength are outlined.

Sign in / Sign up

Export Citation Format

Share Document