Elongate fiber artificial muscles and method of fabrication

Abstract

An elongate fiber artificial muscle includes or consists of an elongate carbon or glass fiber and at least a partial coating of a polymer, and preferably a full shell coating to form a core-shell arrangement, that is volumetrically responsive to thermal changes or to moisture changes. Additional elongate fiber artificial muscles of the invention include a plurality of elongate carbon or glass fibers that are infiltrated between the fibers with a polymer that is volumetrically responsive to thermal changes or to moisture changes. In a fabrication method, the rheology (flow characteristic) of a polymer precursor is adjusted with solvent so it is less viscous. A fiber or plurality of fibers (pre-twisted or untwisted), such as a tow is dipped in the polymer precursor. The fiber or fibers is then pulled out of the polymer precursor and hung to allow polymer to distribute and then cured and can be twisted to coil prior to curing. A model is provided to fabricate elongate fiber artificial muscle with specific characteristics based upon a thermal or moisture expansion coefficient of the polymer, its elongation capability percentage before flaking or breaking, and its elastic modulus.