Animating hydrogel knotbots with topology-invoked self-regulation

Area of Science:

• Soft robotics
• Materials science
• Nonlinear dynamics

Background:

• Self-regulated motion in soft robots is challenging, often requiring complex symmetry breaking and recovery.
• The role of geometric topology in soft robot design is underexplored.
• Existing soft robots struggle with persistent, autonomous locomotion.

Purpose of the Study:

• To introduce knotbots, hydrogel-based robots utilizing knotted structures for autonomous motion.
• To investigate the self-regulation mechanisms enabling continuous movement in soft robots.
• To demonstrate the application of topology in designing advanced soft robotic systems.

Main Methods:

• Fabrication of hydrogel robots with specific knotted topologies.
• Application of external stimuli (light) to induce photothermal strain.
• Experimental observation and computational simulation of robot dynamics.
• Analysis of self-constraint-induced prestress and self-shadowing effects.

Main Results:

• Knotbots exhibit autonomous rolling and spinning/rotating motions.
• Continuous motion is achieved through the interplay of self-constraints, active deformation, and photothermal effects.
• Non-equilibrium processes are dynamically regulated by the robot's structure and environment.
• Demonstrated task execution, including gear rotation and rod climbing.

Conclusions:

• Geometric topology is a viable design principle for achieving self-regulated motion in soft robots.
• Knotbots offer a novel platform for sustainable and autonomous soft robotic actuation.
• This approach opens new avenues for designing sophisticated soft robots with dynamic capabilities.