Chemically Driven Oscillating Soft Pneumatic Actuation

Pneumatic actuators are widely studied in soft robotics as they are facile, low cost, scalable, and robust and exhibit compliance similar to many systems found in nature. The challenge is to harness high energy density chemical and biochemical reactions that can generate sufficient pneumatic pressure to actuate soft systems in a controlled and ecologically compatible manner. This investigation evaluates the potential of chemical reactions as both positive and negative pressure sources for use in soft robotic pneumatic actuators. Considering the pneumatic actuation demands, the chemical mechanisms of the pressure sources, and the safety of the system, several gas evolution/consumption reactions are evaluated and compared. Furthermore, the novel coupling of both gas evolution and gas consumption reactions is discussed and evaluated for the design of oscillating systems, driven by the complementary evolution and consumption of carbon dioxide. Control over the speed of gas generation and consumption is achieved by adjusting the initial ratios of feed materials. Coupling the appropriate reactions with pneumatic soft-matter actuators has delivered autonomous cyclic actuation. The reversibility of these systems is demonstrated in a range of displacement experiments, and practical application is shown through a soft gripper that can move, pick up, and let go of objects. Our approach presents a significant step toward more autonomous, versatile soft robots driven by chemo-pneumatic actuators.

Automated summary

Pneumatic actuators are extensively studied in soft robotics due to their ease of use, low cost, scalability, durability, and natural-comparable compliance. The challenge lies in utilizing high-energy-density chemical and biochemical reactions to generate sufficient pneumatic pressure for controlled and ecologically compatible actuation of soft systems. This investigation assesses the potential of chemical reactions as pressure sources for soft robotic pneumatic actuators, considering actuation demands, pressure source mechanisms, and system safety. Gas evolution/consumption reactions are evaluated and compared, and the coupling of gas evolution and consumption reactions is explored for oscillating systems driven by complementary carbon dioxide evolution and consumption. The possibility of autonomous cyclic actuation is achieved by controlling the speed of gas generation and consumption through adjusting the initial feed material ratios. Reversibility is demonstrated through displacement experiments, and practical application is showcased with a soft gripper capable of moving, picking up and releasing objects. This approach represents a significant advancement towards autonomous and versatile chemo-pneumatic driven soft robots.