Adhesive Contact of a Pressure Tunable, Patterned Elastomer*

Applications like soft robotics and pick-and-place manufacturing benefit from using materials capable of achieving discrete levels of adhesion strength. Many studies have investigated switchable or singular tunable adhesion, but not the former. In this work, we develop a pressure tunable adhesive (PTA) with this capability by patterning an elastomer surface with rigid aspereties. The adhesive strength of the PTA is tuned by controlling the amount of pressure applied to the material. Flat punch indentation testing is used to characterize the adhesion strength of PTAs with varying pattern dimensions (asperity size and spacing). We show that the critical pull-off load , P_c, to separate the flat punch from the PTA increases with the amount of compressive load applied, P_m. Additionally, PTAs with small pattern dimensions have a high sensitivity to P_m. Increasing pattern dimensions reduces sensitivity to P_m and overall adhesion strength. A mechanics analysis is presented to describe the adhesive contact between a rigid body and the PTA. Additionally, we show that pressure tunable adhesion is possible for other thin film-bulk elastomer systems and demonstrate their capabilities for pick and place manufacturing.