Electroactive Tuning of Double-Layered Metamaterials Based on π-Conjugated Polymer Actuators

Novel electroactive metamaterials working in the terahertz (THz) and microwave frequency ranges are demonstrated utilizing π-conjugated polymer actuators. Metamaterials are artificial composite materials based on subwavelength resonant elements called "meta-atoms." The resonant character of meta-atoms typically restricts their operating frequency to a narrow range, therefore it is crucial to make them tunable in order to develop practical devices. A promising tuning scheme is based on changing the mutual position of meta-atoms in a composite. When two meta-atoms are placed in close vicinity such that their near-fields interact, their resonant characteristics can be tuned by altering their relative position and/or orientation. Here linear actuators made from heavily doped polypyrrole films are utilized to change the relative lateral position of two THz metasurfaces, and accordion-shaped origami actuators are used to change the distance between two microwave meta-atoms. In both cases significant tunability of the resonances is obtained by the application of a control voltage. This approach here may open a new direction for creating tunable metamaterials based on a rich variety of π-conjugated polymer actuators.