(594g) A Modified Jkr Model for the Adhesion of a Patterned Surface Against a Smooth Glass Surface

Geckos can quickly attach and detach from surfaces regardless of the surface roughness. This inspired the development of synthetic materials mimicking the gecko adhesive system for robotic applications, which shows advantages over the conventional pressure sensity adhesives.We fabricated arrays of structured PDMS micro-flaps mimicking the functional behavior of the gecko foot-pad and characterized the adhesion properties of these fabricated fibres using a modified Surface Forces Apparatus (SFA). Adhesive properties were investigated for both, normal pure loading and unloading as well as unloading (detachment) after the surfaces were sheared, along and against the direction of tilt of the micro-flaps.Enhanced adhesion was measured on shearing the flaps along the tilted (gripping) direction and low adhesion when sheared against the tilted (releasing) direction. A modified Johnson-Kendall-Roberts (JKR) theory very well described the contact mechanics of these micro-flaps ensemble against the silica surface using an effective surface energy and modulus of rigidity. Implications for the frictional properties of the flaps against smooth and rough silica surfaces are also discussed.