MEAM PHD Thesis Defense: “Control of Dry Adhesion via Mechanics and Structuring”

Dry adhesives that rely on van der Waals forces have a number of applications due to their versatility, reusability, and repeatability. Applications include small-scale pick-and-place and microtransfer printing processes, wearable sensors, climbing/perching robots, and robotic gripping. However, van der Waals forces are macroscopically short-range and are the weakest of the interatomic forces, so careful mechanical design of adhesive structures is required to provide sufficient dry adhesion strength for many of these applications. This thesis investigates the mechanics-based design of structured dry adhesives with enhanced and controllable adhesion.

First, a mechanics-based strategy for achieving the optimum interfacial stress distribution of an elastic layer to realize high adhesion strength is presented. Second, dry adhesion tuning via the control of the interfacial stress distribution via subsurface pressure modulation in soft device is analyzed and demonstrated. Then, the mechanics of adhesion of flat-ended pillars with non-circular contacts to enable the design of fibrillar adhesives with high packing density is investigated. Finally, the mechanics of tunable adhesion in microtransfer printing processes is examined and a strategy to provide robust control of microtransfer printing processes is proposed.