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1. Coupled oscillators and dielectric function

   https://doi.org/10.1103/PhysRevB.111.115101  

   Das, T.; Ullrich, C_A; Jentschura, U_D (March 2025, Physical Review B)
2. 3-D PRINTING OF DIELECTRIC ELECTROACTIVE POLYMER ACTUATORS AND CHARACTERIZATION OF DIELECTRIC FLEXIBLE MATERIALS

   Gonzalez, David; Newell, Brittany; Garcia, Jose; Noble, Lucas; Mamer, Trevor (October 2018, ASME Conference on Smart Materials, Adaptive Structures, and Intelligent Systems (SMASIS))

   Dielectric electroactive polymers are materials capable of mechanically adjusting their volume in response to an electrical stimulus. However, currently these materials require multi-step manufacturing processes which are not additive. This paper presents a novel 3D printed flexible dielectric material and characterizes its use as a dielectric electroactive polymer (DEAP) actuator. The 3D printed material was characterized electrically and mechanically and its functionality as a dielectric electroactive polymer actuator was demonstrated. The flexible 3-D printed material demonstrated a high dielectric constant and ideal stress-strain performance in tensile testing making the 3-D printed material ideal for use as a DEAP actuator. The tensile stress- strain properties were measured on samples printed under three different conditions (three printing angles 0°, 45° and 90°). The results demonstrated the flexible material presents different responses depending on the printing angle. Based on these results, it was possible to determine that the active structure needs low pre-strain to perform a visible contractive displacement when voltage is applied to the electrodes. The actuator produced an area expansion of 5.48% in response to a 4.3 kV applied voltage, with an initial pre-strain of 63.21% applied to the dielectric material. 

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3. Synthesis of second-order nonlinearities in dielectric-semiconductor-dielectric metamaterials

   https://doi.org/10.1063/1.4978640  

   Lin, Hung-Hsi; Yang, Mu-Han; Sharma, Rajat; Puckett, Matthew W.; Montoya, Sergio; Wurm, Christian D.; Vallini, Felipe; Fullerton, Eric E.; Fainman, Yeshaiahu (March 2017, Applied Physics Letters)
4. Dielectric elastomer actuators

   https://doi.org/10.1063/5.0043959  

   Hajiesmaili, Ehsan; Clarke, David R. (April 2021, Journal of Applied Physics)

   Dielectric elastomer actuators (DEAs) are soft, electrically powered actuators that have no discrete moving parts, yet can exhibit large strains (10%–50%) and moderate stress (∼100 kPa). This Tutorial describes the physical basis underlying the operation of DEA's, starting with a simple linear analysis, followed by nonlinear Newtonian and energy approaches necessary to describe large strain characteristics of actuators. These lead to theoretical limits on actuation strains and useful non-dimensional parameters, such as the normalized electric breakdown field. The analyses guide the selection of elastomer materials and compliant electrodes for DEAs. As DEAs operate at high electric fields, this Tutorial describes some of the factors affecting the Weibull distribution of dielectric breakdown, geometrical effects, distinguishing between permanent and “soft” breakdown, as well as “self-clearing” and its relation to proof testing to increase device reliability. New evidence for molecular alignment under an electric field is also presented. In the discussion of compliant electrodes, the rationale for carbon nanotube (CNT) electrodes is presented based on their compliance and ability to maintain their percolative conductivity even when stretched. A procedure for making complaint CNT electrodes is included for those who wish to fabricate their own. Percolative electrodes inevitably give rise to only partial surface coverage and the consequences on actuator performance are introduced. Developments in actuator geometry, including recent 3D printing, are described. The physical basis of versatile and reconfigurable shape-changing actuators, together with their analysis, is presented and illustrated with examples. Finally, prospects for achieving even higher performance DEAs will be discussed. 

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5. Electromechanical characterization of 3D printed dielectric material for dielectric electroactive polymer actuators

   Gonzalez, David; Garcia, Jose; Newell, Brittany (January 2019, Sensors and actuators. A, Physical)

   Dielectric electroactive polymers (DEAPs) represent a subclass of smart materials that are capable of converting between electrical and mechanical energy. These materials can be used as energy harvesters, sensors, and actuators. However, current production and testing of these devices is limited and requires multiple step processes for fabrication. This paper presents an alternate production method via 3D printing using Thermoplastic Polyurethane (TPU) as a dielectric elastomer. This study provides electromechanical characterization of flexible dielectric films produced by additive manufacturing and demonstrates their use as DEAP actuators. The dielectric material characterization of TPU includes: measurement of the dielectric constant, percentage radial elongation, tensile properties, pre-strain effects on actuation, surface topography, and measured actuation under high voltage. The results demonstrated a high dielectric constant and ideal elongation performance for this material, making the material suitable for use as a DEAP actuator. In addition, it was experimentally determined that the tensile properties of the material depend on the printing angle and thickness of the samples thereby making these properties controllable using 3D printing. Using surface topography, it was possible to analyze how the printing path, affects the roughness of the films and consequently affects the voltage breakdown of the structure and creates preferential deformation directions. Actuators produced with concentric circle paths produced an area expansion of 4.73% uniformly in all directions. Actuators produced with line paths produced an area expansion of 5.71% in the direction where the printed lines are parallel to the deformation direction, and 4.91% in the direction where the printed lines are perpendicular to the deformation direction. 

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