Mechanically tunable dry adhesive from wrinkled elastomers

We report a new dry adhesive structure using a rippled poly(dimethylsiloxane) (PDMS) elastomer bilayer film, whose surface roughness and adhesion can be reversibly regulated by applying mechanical strain. It has a set of advantages not offered by other techniques for regulation of adhesion, including real-time tunability, no requirement of specific surface chemistry, operability under ambient conditions, and relative ease of control. To understand the mechanism for adhesion regulation quantitatively, we have modeled the mechanics of adhesion in the limits of small- and large-amplitude ripples, and show good agreement with indentation experiments. We demonstrate the real-time tunability of the new adhesive structure by repeatedly picking and releasing a glass ball simply by modulating the mechanical stretch of the rippled PDMS film.