Gecko-inspired controllable adhesive structures applied to micromanipulation

Gecko-inspired angled elastomer micropillars with flat or round tip endings are presented as compliant pick-and-place micromanipulators. The pillars are 35 μm in diameter, 90 μm tall, and angled at an inclination of 20°. By gently pressing the tip of a pillar to a part, the pillar adheres to it through intermolecular forces. Next, by retracting quickly, the part is picked from a given donor substrate. During transferring, the adhesion between the pillar and the part is high enough to withstand disturbances due to external forces or the weight of the part. During release of the part onto a receiver substrate, the contact area of the pillar to the part is drastically reduced by controlled vertical or shear displacement, which results in reduced adhesive forces. The maximum repeatable ratio of pick-to-release adhesive forces is measured as 39 to 1. It is found that a flat tip shape and shear displacement control provide a higher pick-to-release adhesion ratio than a round tip and vertical displacement control, respectively. A model of forces to serve as a framework for the operation of this micromanipulator is presented. Finally, demonstrations of pick-and-place manipulation of micrometer-scale silicon microplatelets and a centimeter-scale glass cover slip serve as proofs of the concept. The compliant polymer micropillars are safe for use with fragile parts, and, due to exploiting intermolecular forces, could be effective on most materials and in air, vacuum, and liquid environments.