Self-Assembled Asperities for Pressure Tunable Adhesion.

Control of adhesion is important in a host of applications including soft robotics, pick-and-place manufacturing, wearable devices, and transfer printing. While there are adhesive systems with discrete switchability between states of high and low adhesion, achieving continuously variable adhesion strength remains a challenge. In this work, we present a versatile and scalable pressure tunable adhesive (PTA) that is based on the self-assembly of stiff microscale asperities on an elastomeric substrate. We demonstrate that the adhesion strength of the PTA increases with the applied compressive preload due to the unique contact formation mechanism caused by the asperities. Additionally, we develop a contact mechanics model to explain the resulting trends. For a specific PTA design, the critical pull-off force can be increased from 0.4 mN to 30 mN by increasing the applied preload from 1 mN to 30 mN. Finally, we demonstrate the applicability of precision control of adhesion strength by utilizing the PTA for pick-and-place material handling. Our approach in pressure tunable adhesive design based on self-assembly of asperities presents a scalable and versatile approach that is applicable to a variety of material systems having different mechanical or surface properties. This article is protected by copyright. All rights reserved.