Discretely Supported Dry Adhesive Film Inspired by Biological Bending Behavior for Enhanced Performance on a Rough Surface

Abstract

Biologically inspired dry adhesion has recently become a research hot topic because of its practical significance in scientific research and instrumental technology. Yet, most of the current studies merely focus on borrowing the concept from some finer biological contact elements but lose sight of the foundation ones that play an equally important role in the adhesion functionality. Inspired by the bending behavior of the flexible foundation element of a gecko (lamellar skin) in attachment motion, in this study, a new type of dry adhesive structure was proposed, wherein a mushroom-shaped micropillar array behaving as a strongly adhesive layer was engineered on a discretely supported thin film. We experimentally observed and analytically modeled the structural deformation and found that the energy penalty could be largely reduced because of the partial shift from pillar bending to film bending. Such behavior is very analogous in functionality to the lamellar skin in a gecko's pads and is helpful in effectively limiting the damage of the contact interface, thus generating enhanced adhesion even on a rough surface.

Soft Robotic Grippers

“…For the former, a potential solution can be the optimization of the shape and materials of the microfibers. Enhancing the bending behavior of geckoadhesion pillars has led to improved adhesion performance on rough surfaces . Microspines are also a good candidate that showed excellent grasping ability on rough surfaces such as of concrete and rocks .…”

Multiscale Soft–Hard Interface Design for Flexible Hybrid Electronics

“…[39] Later, an optimized design using a mushroomshaped micropillar array was reported to further enhance the surface area between microhairs and substrates. [212] The proposed structures showed high adhesive strength up to 22.5 kPa against glass substrates. More importantly, the structure could also generate strong adhesion (up to 2.9 kPa) on uneven substrates with convex cylinders and closely packed hexagonal pyramids.…”

“…Compared to the flat PDMS supported sensors, the microhairy sensors exhibited 12‐fold enhancement in the signal‐to‐noise ratio in detecting wrist pulse . Later, an optimized design using a mushroom‐shaped micropillar array was reported to further enhance the surface area between microhairs and substrates . The proposed structures showed high adhesive strength up to 22.5 kPa against glass substrates.…”

Mechanics of Crater-Enabled Soft Dry Adhesives: A Review

“…Based on this scaling law, aside from enlarging effective contact area A, the adhesive force may also be enhanced by decreasing the system compliance C. An easy way to minimize the compliance C is by utilizing stiff materials. Here, we summarize existing data from the literature in an Ashby plot ( Figure 3, numbers are listed in Table 1 and Table 2) where the experimentally measured normal adhesive strength is plotted versus material Young's modulus (Geim et al, 2003;Sitti and Fearing, 2003;Kim and Sitti, 2006;Del Campo et al, 2007b;Lee et al, 2008;Lu et al, 2008;Cheung and Sitti, 2009;Davies et al, 2009;Murphy et al, 2009;Parness et al, 2009;Sameoto and Menon, 2009;Kwak et al, 2011;Bae et al, 2013;Tsai and Chang, 2013;Jin et al, 2014;Fischer et al, 2016;Kim et al, 2016;Drotlef et al, 2017;Hu et al, 2017). In this plot, the purple zone represents pillarbased adhesives in dry environments, the orange zone highlights crater-based adhesives under normal ambient conditions, and the green zone indicates crater-based adhesives under high humidity, wet or underwater environments.…”