Dielectric Elastomer Architectures with Strain‐Tunable Permittivity

Flexible hybrid electronic (FHE) materials and devices exploit the interaction of mechanical and electromagnetic properties to operate in new form factors and loading environments, which are key for advancing wearable sensors, flexible antennas, and soft robotic skin technologies. Dielectric elastomer (DE) architectures offer a novel substrate material for this application space as they are a class of strain-tolerant and programmable metamaterials that derive their mechanical and dielectric properties from their architecture. Due to their hyperelasticity, dielectric elastomers can leverage reversible finite deformation to physically reconfigure their internal architecture to repeatedly tune their material behavior. Here a combined computational and experimental study of two dielectric elastomer architectures, based on square and hexagonal unit cell periodicities are presented. A shift in effective permittivity is observed due to the relative increase in matrix volume and the rearrangement of the electric field distribution in the cells. Additive fabrication allows rapid unit cell geometry customization for tuning the electromechanical response of the architectures. Effective permittivity shifts Delta epsilon(2) > 0.7 under compressive strains of 35% are observed. The practical utility of this strain-tunable permittivity is demonstrated in a microstrip patch antenna, which exhibits shifts in resonance frequency greater than 110 MHz when the dielectric elastomer substrate is compressed.