Control vs Autonomy in Soft Matter Movement

ABSTRACT

From robotics to advanced manufacturing, engineering technologies are aiming for the development of systems that can be increasingly autonomous. However, examples from nature show us that a balanced approach of providing autonomous functionality with the ability to over-ride and control deviations to an expected behavior is preferred, and can often lead to enhanced performance and even survivability. In this presentation, we will present recent projects that address autonomous and control-enhanced movements, with a focus on the development of materials that can provide self-regenerating, sustained responses. We first introduce materials science principles and lessons that we have learned as part of a multi-university team, which takes inspiration from examples in nature including mantis shrimp, trap-jaw ants, and Venus flytrap plants. These organisms use Latch-Mediated Spring Actuation (LaMSA) to achieve high power, impulsive movements by integrating actuators, elastic elements, and stability-mediating latches. We demonstrate how transient metastable deformations associated with swelling and deswelling of a polymer gel can be exploited to generate mechanical bi-stability, giving rise to multiple, self-repeating, snap-through movements. Second, we describe the use of structural asymmetry to mediate swelling/deswelling processes in order to control the kinematics of mesoscale polymer ribbons. We use this control to form bundled structures that resemble powerful biological actuators, e.g. muscles, and their formation processes open pathways for creating a future generation of materials that have textile-like properties without requiring energy intensive spinning and weaving processes. Collectively, the strategies and results discussed here provide new insight into how polymer properties can combine with purposeful structural design to achieve complex tasks, which can be used in the development of microscale robots and new adaptable composite materials.

BIOGRAPHY

Alfred J. Crosby is Professor and Head of the Polymer Science & Engineering Department at the University of Massachusetts Amherst. He leads a research group focused on bioinspired materials mechanics, covering topics ranging from adhesion to complex assembly to high power actuation. Al received his B.S. in Civil Engineering and Applied Mechanics from the University of Virginia and his Ph.D. in Materials Science & Engineering from Northwestern University. He was an NRC Postdoctoral Fellow at NIST before joining UMass Amherst in 2002. He has received numerous awards, including being a Fellow of the American Physical Society and the National Academy of Inventors, and his research has been covered extensively in the popular media. He serves on several advisory boards and is the Editor-in-Chief for the Royal Society of Chemistry journal Soft Matter.