Self-Cleaning and Controlled Adhesion of Gecko Feet and Their Bioinspired Micromanipulators
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Self-Cleaning and Controlled Adhesion of Gecko Feet and Their Bioinspired Micromanipulators Yiyang Wan, Zhenhai Xia* Department of Materials Science and Engineering, Department of Chemistry, University of North Texas, Denton, TX 76203, USA.
*email: [email protected].
ABSTRACT
Bioinspired micromanipulators have been made based on gecko dynamic self-cleaning mechanism. Various particles such as spherical SiO2/polystyrene, and short fibrous glass can be captured, transmitted and dropped on glass substrate with precisely predesigned patterns, by using the micromanipulator with the help of atomic force microscope (AFM). It has been demonstrated that particle-pad interface and particle-substrate interface exhibit diverse adhesion behaviors under different z-piezo retracting speed. The particle-substrate adhesion increases faster than the particle-pad adhesion with increasing the detaching velocity, which makes it possible to manipulate the particles by adjusting the retreating speed only. Probability tests was performed to better choose suitable parameters for picking and dropping operations. This work provides a potential solution to manipulation of micro/nano particles for precise assembly.
INTRODUCTION Geckos have special ability to walk on various kinds of surfaces, indicating that their feet are of high adhesion. It was reported that gecko generate adhesion making use of van der Waals force.[1,2] What makes it more interesting is the self-cleaning properties of gecko setae,[3] which means gecko seta adhesion is well controllable: they generate high adhesion but do not adhere to dirty particles. Inspired by the remarkable ability of gecko, some groups fabricated seta-like structures for adhesive surface.[4,5] This surface is able to keep sticky on dusty substrates. In our previous work, we have discovered a unique mechanism for gecko self-cleaning: the adhesion is significantly affected by retracting velocity.[6] When retracting speed increases, the adhesive force between particle and substrate is enhanced dramatically, providing us potential way to manipulate by changing pull-off velocity. A micro-manipulator was made with polyester fiber and graphene gluing at the end. Due to high adhesive force observed on the graphene[7], similar adjustable stickiness was achieved using the graphene material. However, the detailed mechanism is still unclear for the self-cleaning and manipulation. In this paper, the effect on the manipulator, including dynamic, shear movement and geometry of fiber/cantilever, will be further investigated. More
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parameters were considered to better control the adhesive force, to achieve more accurate manipulation of microparticles. SiO2, Polystyrene microsphere and microfiber segments were tested on glass and sapphire substrate, in normal dr
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