Dielectric Elastomer Architectures with Strain‐Tunable Permittivity

Abstract

than their intrinsic material constituents. Metamaterials concepts have been demonstrated in diverse fields, including electromagnetics, acoustics, mechanics and others, exhibiting novel properties such as negative refractive index, perfect absorption, and auxetic behavior. [1][2][3][4][5] Further, metamaterials can be designed with flexible and reconfigurable substrates to achieve physically tunable responses. For instance, several examples of origami and deployable structures exhibit adaptive electromagnetic resonance tuning through physical deformation. [6][7][8][9][10] Strain-tunable dielectric materials and composites are a growing research field with recent demonstrations in optical and millimeter wave regimes. [11,12] For instance, Meerbeek et al., described the macroscopic shape of a porous elastomeric foam by measuring the shift in light reflected internally by its cellular voids during bending and twisting. [11] Zhang et al., synthesized a graphene foam with tunable microwave absorption via solid matrix densification during physical compression. [13] Additional mechanisms for strain-tuning dielectric properties include the use of permanent or induced dipoles at the molecular level; and the distribution of voids and inclusions in host matrices. [14][15][16] Elastomeric metamaterials present a deformation-based tuning strategy for regulating local periodicity and effective dielectric properties. This strategy is particularly useful in deformable electromagnetic devices where the feature size of the dielectric architecture is electrically small and physical reconfiguration of the dielectric structure will facilitate localized and controllable tuning. [14] Materials with mechanically reconfigurable dielectric properties can help address these inherent challenges for flexible hybrid electronics (FHEs) and adaptive communication devices.Elastomers have previously been leveraged for mechanical metamaterials, which are a subset of metamaterial designs with periodic architectures whose elements rotate, buckle, fold, or snap under an external load. [17] Mechanical instabilities present in many of these structures allow their rapid transformation under relatively low strains. They demonstrate unique properties like auxetic behavior, energy absorption, multistability, and nonlinear elastic properties. [18][19][20][21][22][23][24][25] The transformation of these mechanical structures provides a straightforward tuning mechanism for surrounding wave properties in optical, acoustic, and 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 the...

Ultrasound generation in water via quasi-periodically snapping polymeric core–shell micro-bead excited with radiowaves

“…To calculate the two parameters are then necessary two sets of ). In the present work we are working in the frequency band of few hundreds MHz that is a low frequency regime compared to common applications of this type of polymer (or similar) in the GHz range 34 – 37 . Therefore we enforced the same values of = 0.1 38 at the extremal values of the investigated frequency range and this return the sought values of .…”

Mechanical Properties of Highly Deformable Elastomeric Gyroids for Multifunctional Capacitors

“…[1][2][3] Applications include tissue engineering, [4][5][6] actuators, [7][8][9][10][11][12][13] heat exchangers, [14,15] and energy storage devices. [16,17] Metamaterials can modify the mechanical, [18][19][20][21][22][23][24] electrical, [16,17,25] acoustic, [26][27][28][29][30][31] optical, [32][33][34] fluidic, [35,36] and thermal [14,15,37] behavior of devices and structures. Triply periodic minimal surface (TPMS) lattices are a well defined subcategory of metamaterials.…”