IDEA #7SV3LH Silk-composite-based water-responsive actuators. 24A0023.

Key Words: Evaporation energy, clean energy, hygroscopic materials, water-responsive materials, fiber actuators The present invention includes a series of microscale linear actuators/muscles by integrating water-responsive (WR) nanoscale Bacillus subtilis peptidoglycan (PG) into Bombyx (B.) mori silk protein. These PG/silk composite fibers are generated using the wet-spinning technique. As discussed in further details later, the fiber actuator exhibits reversible linear actuation under ambient conditions upon exposure to varying relative humidity (RH) and could lead to a new class of actuators/artificial muscles with high energy/power densities and a relatively long lifespan, surpassing those observed in other forms of conventional actuator materials and muscles. Different from current actuators/artificial muscles that usually require high pressure gas/liquid, high voltage/powers, or high temperatures, the proposed WR fiber actuator could provide >100 MPa actuation pressure by injecting low pressure dry and humid air, and thus provide new opportunities for removing design constraints of many robotic systems. The purpose of this invention is to provide proof-of-concept demonstrations for the use of muscle-like WR fiber actuators in powering practical applications such as soft robotics, submerged vehicles, and exoskeletons. For example, we expect that the new class of WR actuator is capable of operating against significant water pressure even in the deepest part of Earth’s oceans. The research activities and outcomes will, in the long term, enhance warfighter resilience and performance.
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