Self‐Sensing Archimedean Spiral Artificial Muscle Fibers with Bidirectional Actuation for Electromagnetic Wave/Light Modulation and Mechanical Display

Abstract The coiled structure acts as a performance “amplifier” role in linearly contracted artificial muscle fibers. However, the fiber contraction is limited when adjacent coils are in contact, and integrating the self‐sensing function after further increasing the actuation stroke is still challenging. A self‐sensing artificial muscle fiber with bidirectional actuation is reported, obtained by twisting a silver‐plated nylon yarn fiber and a silver‐plated nylon yarn@polyimide (PI) fiber together and then winding to form an Archimedean spiral. Bare nylon fiber, nylon@PI fiber, and PI film enable electrothermal, sensing, and insulation functions, respectively, and all materials provide actuation features. Noteworthy, this Archimedean spiral structure allows adjacent coils to pass through each other during contraction, resulting in a deformation actuation that switches between 2D and 3D. When the twisting and winding directions of the two fibers are the same or opposite, the muscle fibers generate a maximum contraction of ≈100% or a maximum elongation of >2000%, respectively, all of which are accompanied by the self‐sensing function. On the basis of the unique actuation characteristics of these muscle fibers, application demonstrations of electromagnetic wave/light modulation and mechanical display are designed, which provide excellent insights into the innovative development of smart electronic devices in the future.