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Abstract Highly tunable dry adhesion has practical ramifications in robotic manipulation. While grippers based on mechanical interlocking and suction are adopted in various industries, soft grippers that can handle small and delicate objects reliably are yet to be invented. In this paper, it is reported that the presence of an adhesive substrate against a negatively pressurized soft hemispherical shell can significantly delay buckling of the shell. The net adhesion strength of such a depressurized shell can reach 60 times that of an open shell without any pressure difference. Simultaneous measurements of internal pressure, mechanical tension, contact area, and approach distance agree well with a semi‐analytical solid‐mechanics model. Introduction of defects at the polar region of the shells does not affect adhesion under the depressurized condition but significantly reduces adhesion under no pressure, leading to even higher tunability (almost infinity). The enhanced adhesion of a depressurized shell is found to be a combined effect of dry adhesion and suction. These shell grippers are shown to be effective in the universal manipulation of various objects with wide ranges of weight, shape, surface roughness, and mechanical compliance. The proposed depressurized soft shells provide a promising robotic gripping platform for industrial adoption.
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Tunable Dry Adhesion of Soft Hollow Pillars through Sidewall Buckling under Low Pressure
Abstract Controlling adhesion on demand is essential for many manufacturing and assembly processes such as microtransfer printing. Among various strategies, pneumatics‐controlled switchable adhesion is efficient and robust but currently still suffers from challenges in miniaturization and high energy cost. In this paper, a novel way to achieve tunable adhesion using low pressure by inducing sidewall buckling in soft hollow pillars (SHPs) is introduced. It is shown that the dry adhesion of these SHPs can be changed by more than two orders of magnitude (up to 151×) using low activating pressure (≈−10 or ≈20 kPa). Large enough negative pressure triggers sidewall buckling while positive pressure induces sidewall bulging, both of which can significantly change stress distribution at the bottom surface to facilitate crack initiation and reduce adhesion therein. It is shown that a single SHP can be activated by a micropump to manipulate various lightweight objects with different curvatures and surface textures. Here, it is also demonstrated that an array of SHPs can realize selective pick‐and‐place of an array of objects. These demonstrations illustrate the robustness, simplicity, and versatility of these SHPs with highly tunable dry adhesion.
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- PAR ID:
- 10381437
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 33
- Issue:
- 2
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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