An Adaptation of the Split-Cylinder Resonator Method for Measuring the Microwave Properties of Thin Ferroelectric Films in a "Thin Film-Substrate" Structure.

The split-cylinder resonator method was adapted to measure the microwave properties (dielectric permittivity and loss tangent) of thin ferroelectric films on a dielectric substrate. The mathematical model for calculating the resonance frequency of the split-cylinder resonator was adjusted for the "ferroelectric film-substrate" structure. An approach for correcting the gap effect based on calibrating with a single-layer dielectric was introduced and used to study two-layer dielectrics. The prototype of a split-cylinder resonator designed to measure single-layer dielectric plates at a frequency of 10 GHz was presented. The resonator calibration was performed using dielectric PTFE samples and fused silica, and an example of the correction function was suggested. The measurement error was estimated, and recommendations on the acceptable parameter range for the material under investigation were provided. The method was demonstrated to measure the microwave properties of a ferroelectric film on a fused silica substrate.

A Novel Strategy for Detecting Permittivity and Loss Tangent of Low-Loss Materials Based on Cylindrical Resonant Cavity.

Accurate measurement of the permittivity and loss tangent of low-loss materials is essential due to their special applications in the field of ultra large scale integrated circuits and microwave devices. In this study, we developed a novel strategy that can accurately detect the permittivity and loss tangent of low-loss materials based on a cylindrical resonant cavity supporting the TE111 mode in X band (8-12 GHz). Based on an electromagnetic field simulation calculation of the cylindrical resonator, permittivity is precisely retrieved by exploring and analyzing the perturbation of the coupling hole and sample size on the cutoff wavenumber. A more precise approach to measuring the loss tangent of samples with various thicknesses has been proposed. The test results of the standard samples verify that this method can accurately measure the dielectric properties of samples that have smaller sizes than the high Q cylindrical cavity method.

Multi-nanocavities and multi-defects synergetic enhancement for the electromagnetic absorption of the rGO-NG film.

Dielectric loss is an important way to eliminate electromagnetic pollution. In order to achieve high dielectric loss, a graphene film reduced graphene oxide-N doped graphene (rGO-NG) was constructed from graphene oxide-Ni@polydopamine (GO-Ni@PDA) via thein situsynthesis of hollow graphene spheres between graphene sheets. Thisin situwas achieved by means of electrostatic self-assembly and metal-catalyzed crystallization. Owing to the synergetic effect of multi-nanocavities and multi-defects, the prepared rGO-NG film shows an average shielding effectiveness (SE) of 50.0 dB in the range of 8.2-12.4 GHz with a thickness of 12.2µm, and the SE reflection is only 7.3 dB on average. It also exhibits an average dielectric loss tangent (tanδ) of 23.1, which is 26 and 105 times higher than those of rGO and rGO-Ni, respectively. This work provides a simple but effective route to develop high performance graphene-based materials for application as an electromagnetic interference shielding film in today's electronic devices.

High-Sensitivity Slot-Loaded Microstrip Patch Antenna for Sensing Microliter-Volume Liquid Chemicals with High Relative Permittivity and High Loss Tangent.

This paper proposes a microwave sensor based on a high-sensitivity slot-loaded rectangular microstrip patch antenna (MPA) for measuring microliter-volume liquid chemicals with high relative permittivity and high loss tangent. A rectangular single-ring complementary split ring resonator (SR-CSRR) slot with a bottom-edge center split (BCS) was inserted along the upper radiating edge of the patch to enhance the relative permittivity sensitivity of the MPA. The first resonant frequency of the proposed SR-CSRR-BCS slot-loaded MPA showed the highest sensitivity compared to the resonant frequencies of the MPAs with other commonly used slots for varying the relative permittivity of the planar substrate type material under test from 1 to 10 when placed above the patch. After designing the scaled SR-CSRR-BCS slot-loaded MPA with the unloaded first resonant frequency at 2.5 GHz, a hollow acrylic cylindrical liquid container with an inner volume of approximately 18.6 µL was placed at the top-edge center of the SR-CSRR-BCS slot to achieve maximum sensitivity. A quarter-wavelength transformer was applied between the patch and the feed line of the MPA to improve the impedance mismatch that occurs when liquid chemicals with a high loss tangent are placed in the container. Water, methanol, and ethanol were carefully selected for test liquids to cover a broad range of relative permittivity and high loss tangents. The proposed SR-CSRR-BCS slot-loaded MPA was designed and fabricated on a 0.76 mm-thick RF-35 substrate, and a reference RS-loaded MPA was designed and fabricated for comparison. The shift in the first resonant frequency of the input reflection coefficient characteristic was used for the sensitivity comparison, and the container was filled with 15 µL of the liquids at 25 °C. The measured sensitivity (%) of the proposed SR-CSRR-BCS slot-loaded MPA for water was 0.45%, which was higher than other antenna-based microwave sensors in the literature.

Dielectric Responses of (Zn0.33Nb0.67)xTi1-xO2 Ceramics Prepared by Chemical Combustion Process: DFT and Experimental Approaches.

The (Zn, Nb)-codoped TiO2 (called ZNTO) nanopowder was successfully synthesized by a simple combustion process and then the ceramic from it was sintered with a highly dense microstructure. The doped atoms were consistently distributed, and the existence of oxygen vacancies was verified by a Raman spectrum. It was found that the ZNTO ceramic was a result of thermally activated giant dielectric relaxation, and the outer surface layer had a slight effect on the dielectric properties. The theoretical calculation by using the density functional theory (DFT) revealed that the Zn atoms are energy preferable to place close to the oxygen vacancy (Vo) position to create a triangle shape (called the ZnVoTi defect). This defect cluster was also opposite to the diamond shape (called the 2Nb2Ti defect). However, these two types of defects were not correlated together. Therefore, it theoretically confirms that the electron-pinned defect-dipoles (EPDD) cannot be created in the ZNTO structure. Instead, the giant dielectric property of the (Zn0.33Nb0.67)xTi1-xO2 ceramics could be caused by the interfacial polarization combined with electron hopping between the Zn2+/Zn3+ and Ti3+/Ti4+ ions, rather than due to the EPDD effect. Additionally, it was also proved that the surface barrier-layer capacitor (SBLC) had a slight influence on the giant dielectric properties of the ZNTO ceramics. The annealing process can cause improved dielectric properties, which are properties with a huge advantage to practical applications and devices.

Radar-Sounding Characterization of the Subglacial Groundwater Table Beneath Hiawatha Glacier, Greenland.

Radar-sounding surveys associated with the discovery of a large impact crater beneath Hiawatha Glacier, Greenland, revealed bright, flat subglacial reflections hypothesized to originate from a subglacial groundwater table. We test this hypothesis using radiometric and hydrologic analysis of those radar data. The dielectric loss between the reflection from the top of the basal layer and subglacial reflection and their reflectivity difference represent dual constraints upon the complex permittivity of the basal material. Either ice-cemented debris or fractured, well-drained bedrock explain the basal layer's radiometric properties. The subglacial reflector's geometry is parallel to isopotential hydraulic head contours, located 7.5-15.3 m below the interface, and 11 ± 7 dB brighter than the ice-basal layer reflection. We conclude that this subglacial reflection is a groundwater table and that its detection was enabled by the wide bandwidth of the radar system and unusual geologic setting, suggesting a path for future direct radar detection of subglacial groundwater elsewhere.

The Primary Origin of Excellent Dielectric Properties of (Co, Nb) Co-Doped TiO2 Ceramics: Electron-Pinned Defect Dipoles vs. Internal Barrier Layer Capacitor Effect.

(Co, Nb) co-doped rutile TiO2 (CoNTO) nanoparticles with low dopant concentrations were prepared using a wet chemistry method. A pure rutile TiO2 phase with a dense microstructure and homogeneous dispersion of the dopants was obtained. By co-doping rutile TiO2 with 0.5 at.% (Co, Nb), a very high dielectric permittivity of ε' ≈ 36,105 and a low loss tangent of tanδ ≈ 0.04 were achieved. The sample-electrode contact and resistive outer-surface layer (surface barrier layer capacitor) have a significant impact on the dielectric response in the CoNTO ceramics. The density functional theory calculation shows that the 2Co atoms are located near the oxygen vacancy, creating a triangle-shaped 2CoVoTi complex defect. On the other hand, the substitution of TiO2 with Nb atoms can form a diamond-shaped 2Nb2Ti complex defect. These two types of complex defects are far away from each other. Therefore, the electron-pinned defect dipoles cannot be considered the primary origins of the dielectric response in the CoNTO ceramics. Impedance spectroscopy shows that the CoNTO ceramics are electrically heterogeneous, comprised of insulating and semiconducting regions. Thus, the dielectric properties of the CoNTO ceramics are attributed to the interfacial polarization at the internal insulating layers with very high resistivity, giving rise to a low loss tangent.

Influences of Sr2+ Doping on Microstructure, Giant Dielectric Behavior, and Non-Ohmic Properties of CaCu3Ti4O12/CaTiO3 Ceramic Composites.

The microstructure, dielectric response, and nonlinear current-voltage properties of Sr2+-doped CaCu3Ti4O12/CaTiO3 (CCTO/CTO) ceramic composites, which were prepared by a solid-state reaction method using a single step from the starting nominal composition of CCTO/CTO/xSrO, were investigated. The CCTO and CTO phases were detected in the X-ray diffraction patterns. The lattice parameter increased with increasing Sr2+ doping concentration. The phase compositions of CCTO and CTO were confirmed by energy-dispersive X-ray spectroscopy with elemental mapping in the sintered ceramics. It can be confirmed that most of the Sr2+ ions substituted into the CTO phase, while some minor portion substituted into the CCTO phase. Furthermore, small segregation of Cu-rich was observed along the grain boundaries. The dielectric permittivity of the CCTO/CTO composite slightly decreased by doping with Sr2+, while the loss tangent was greatly reduced. Furthermore, the dielectric properties in a high-temperature range of the Sr2+-doped CCTO/CTO ceramic composites can be improved. Interestingly, the nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were significantly enhanced. The improved dielectric and nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were explained by the enhancement of the electrical properties of the internal interfaces.

Detecting Traces of 17α-Ethinylestradiol in Complex Water Matrices.

Hormones have a harmful impact on the environment and their detection in water bodies is an urgent matter. In this work, we present and analyze a sensor device able to detect traces of the synthetic hormone 17α-ethinylestradiol (EE2) below 10-9 M in media of different complexities, namely, ultrapure, mineral and tap waters. This device consists of solid supports with interdigitated electrodes without and with a polyethylenimine (PEI) and poly (sodium 4-styrenesulfonate) (PSS) layer-by-layer film deposited on it. Device response was evaluated through capacitance, loss tangent and electric modulus spectra and the data were analyzed by principal component analysis method. While the three types of spectra were demonstrated to be able to clearly discriminate the different media, loss tangent spectra allow for the detection of EE2 concentration, with a sensitivity of -0.072 ± 0.009 and -0.44 ± 0.03 per decade of concentration, for mineral and tap water, respectively. Detection limits values were found to be lower than the ones present in the literature and presenting values of 8.6 fM (2.6 pg/L) and of 7.5 fM (22.2 pg/L) for tap and mineral waters, respectively. Moreover, the obtained response values follow the same behavior with EE2 concentration in any medium, meaning that loss tangent spectra allow the quantification of EE2 concentration in aqueous complex matrices.

Ion Transport Study in CS: POZ Based Polymer Membrane Electrolytes Using Trukhan Model.

In this work, analysis of ion transport parameters of polymer blend electrolytes incorporated with magnesium trifluoromethanesulfonate (Mg(CF3SO3)2) was carried out by employing the Trukhan model. A solution cast technique was used to obtain the polymer blend electrolytes composed of chitosan (CS) and poly (2-ethyl-2-oxazoline) (POZ). From X-ray diffraction (XRD) patterns, improvement in amorphous phase for the blend samples has been observed in comparison to the pure state of CS. From impedance plot, bulk resistance (Rb) was found to decrease with increasing temperature. Based on direct current (DC) conductivity (σdc) patterns, considerations on the ion transport models of Arrhenius and Vogel-Tammann-Fulcher (VTF) were given. Analysis of the dielectric properties was carried out at different temperatures and the obtained results were linked to the ion transport mechanism. It is demonstrated in the real part of electrical modulus that chitosan-salt systems are extremely capacitive. The asymmetric peak of the imaginary part (Mi) of electric modulus indicated that there is non-Debye type of relaxation for ions. From frequency dependence of dielectric loss (ε″) and the imaginary part (Mi) of electric modulus, suitable coupling among polymer segmental and ionic motions was identified. Two techniques were used to analyze the viscoelastic relaxation dynamic of ions. The Trukhan model was used to determine the diffusion coefficient (D) by using the frequency related to peak frequencies and loss tangent maximum heights (tanδmax). The Einstein-Nernst equation was applied to determine the carrier number density (n) and mobility. The ion transport parameters, such as D, n and mobility (µ), at room temperature, were found to be 4 × 10-5 cm2/s, 3.4 × 1015 cm-3, and 1.2 × 10-4 cm2/Vs, respectively. Finally, it was shown that an increase in temperature can also cause these parameters to increase.

MR elastography of the liver and the spleen using a piezoelectric driver, single-shot wave-field acquisition, and multifrequency dual parameter reconstruction.

PURPOSE: Viscoelastic properties of the liver are sensitive to fibrosis. This study proposes several modifications to existing magnetic resonance elastography (MRE) techniques to improve the accuracy of abdominal MRE. METHODS: The proposed method comprises the following steps: (i) wave generation by a nonmagnetic, piezoelectric driver suitable for integration into the patient table, (ii) fast single-shot 3D wave-field acquisition at four drive frequencies between 30 and 60 Hz, and (iii) single-step postprocessing by a novel multifrequency dual parameter inversion of the wave equation. The method is tested in phantoms, healthy volunteers, and patients with portal hypertension and ascites. RESULTS: Spatial maps of magnitude and phase of the complex shear modulus were acquired within 6-8 min. These maps are not subject to bias from inversion-related artifacts known from classic MRE. The spatially averaged modulus for healthy liver was 1.44 ± 0.23 kPa with ϕ = 0.492 ± 0.064. Both parameters were significantly higher in the spleen (2.29 ± 0.97 kPa, P = 0.015 and 0.749 ± 0.144, P = 6.58·10(-5) , respectively). CONCLUSION: The proposed method provides abdominal images of viscoelasticity in a short time with spatial resolution comparable to conventional MR images and improved quality without being compromised by ascites. The new setup allows for the integration of abdominal MRE into the clinical workflow.

Water absorption in artificial composites: Curse or blessing?

OBJECTIVES: This study evaluated the impact of mutable water uptake on the durability of mechanical properties and the long-term reliability of artificial composites. METHODS: Three resin-based CAD/CAM restorative materials (CRMs) were investigated in three-point bending tests to calculate flexural strength (FS), modulus of elasticity (ME), modulus of resilience (MR), modulus of toughness (MT), and elastic recovery (ER). All specimens (n = 180) were stored under the same conditions and tested in four subsets (n = 15 per material) that were respectively withdrawn after repeated thermocycling (5000 cycles; 5-55 °C, H2O) and repetitive drying (7 d; 37 °C, air). For every specimen, weight differences were determined per storage condition. Likewise, loss tangent data were separately recorded via dynamic mechanical analysis to reliably assess damping characteristics. RESULTS: Repeated thermocycling always induced weight increase and a concurrent significant loss in all mechanical properties except for MT and ER of a polymethylmethacrylate-based CRM. Drying consistently provoked weight loss and raised mechanical properties to initial values. Weight increase, however, enhanced loss tangent values and accordingly distinct damping characteristics, whereas weight decrease markedly lowered damping properties. SIGNIFICANCE: Water uptake repeatedly induced a decrease in common mechanical properties but concurrently increased damping behavior. Invertible equilibrium processes were found with no evidence for permanent material degradation.

Innovative soil fluoride estimation method: dual polarimetric saline-associated fluoride for agricultural patches.

Fluoride and its constituents in soil affect plant growth and public health. In this study, soil fluoride was measured for the semi-arid regions in southern India, using Sentinel-1 data in conjunction with the dual polarimetric saline-associated fluoride model (also known as fluoride model). A loss angle was estimated from laboratory-based dielectric components of soil samples with strong electrical conductivity under high and low fluoride conditions. The conductivity loss angle and real and imaginary dielectric constants were used to study fluoride salt's dielectric behavior. The imaginary dielectric component sensitive to dielectric loss could predict fluoride across large areas over time. This was statistically analyzed with R2 = 0.86, RMSE = 1.90, and bias = 0.35 showing a promising depiction that C-band SAR data can distinguish fluoride levels over varied clay soil and soil with varying vegetation development. Moreover, the association between biomass and simulated fluoride helped to identify fluoride-tolerant and non-tolerant crops. The study found that Sorghum and Oryza sativa tolerate saline-associated fluoride, whereas Peanut and Allium do not. Furthermore, the model successfully retrieves fluoride from saline salts based on tangent loss.

Interrelationship between viscosity and electrical properties for edible oils.

Electrical properties of edible oil depend upon its total polar component, temperature and the frequency of the applied voltage. Dielectric constant, dielectric loss tangent and electrical conductivity were measured for cottonseed (Gossypium sp.), ground nut (Apios americana), mustard (Brasicca compestriss) and sun flower (Helianthus annuus) oils in the temperature range of 20 to 100°C so as to assess the potential of their applicability for assessing the quality of oils. Viscosity of the oils is an other important physical property associated with their processing and quality control. Viscosity of these oils was experimentally measured. The correlation of viscosity with dielectric loss tangent and viscosity with electrical conductivity were tested. The best correlating relations along with correlation constants, valid for the temperature range of 20-100°C are presented. The regression equation developed relating viscosity with loss tangent and electrical conductivity had high correlation coefficient (R(2) > 0.96) for all the four oils within temperature range of 20-100°C.

Significantly improved giant dielectric properties and enhanced nonlinear coefficient of Ni2+ doped CaCu3Ti4O12/CaTiO3 composites.

CaCu3-xNixTi4O12/CaTiO3 ceramic composites were fabricated using initial Ca2Cu2-xNixTi4O12 compositions (x = 0, 0.05, 0.10, and 0.20) to improve the dielectric properties (DPs) of the CaCu3Ti4O12 ceramics. CaCu3Ti4O12 and CaTiO3 phases were confirmed. Microstructural analysis and Rietveld refinement showed that the Ni2+ dopant might substitute the Cu2+ sites of the CaCu3Ti4O12 structure. The average grain sizes of CaCu3Ti4O12 (4.1-5.6 µm) and CaTiO3 (1.2-1.4 µm) changed slightly with the Ni2+ doping concentration. The best DPs were obtained for the CaCu3-xNixTi4O12/CaTiO3 with x = 0.2. The loss tangent was significantly reduced by an order of magnitude compared to that of the undoped composite, from tanδ∼0.161 to ∼0.016 at 1 kHz, while the dielectric permittivity slightly decreased from ε'∼5.7 × 103 to ∼4.0 × 103. Furthermore, the temperature dependence of ε' could be improved by doping with Ni2+. The improved DPs were caused by the enhanced electrical responses of the internal interfaces, which resulted in enhanced non-Ohmic properties. The largest nonlinear coefficient (α∼7.6) was obtained for the CaCu3-xNixTi4O12/CaTiO3 with x = 0.05. Impedance spectroscopy showed that the CaCu3-xNixTi4O12/CaTiO3 composites consisted of semiconducting and insulating components. The DPs of CaCu3-xNixTi4O12/CaTiO3 were explained based on the space-charge polarization at the active-interfaces.

Extremely reduced loss tangent with retaining ultra high dielectric permittivity in Mg2+-doped La1.9Sr0.1NiO4 ceramics.

An extremely reduced loss tangent while retaining ultrahigh dielectric permittivity can be successfully obtained in La1.9Sr0.1NiO4 ceramics by doping with Mg2+ ions. A single phase of La1.9Sr0.1NiO4 was detected in all the sintered ceramics, while the lattice parameters increased with increasing doping concentration, indicating that Mg2+ ions can enter the Ni2+ sites. A highly dense microstructure is achieved. Microstructural analysis revealed that Mg2+ ions disperse well in the microstructure of La1.9Sr0.1NiO4 ceramics. Interestingly, ultra-high dielectric permittivity of approximately 8.11 × 105 at 1 kHz is achieved in the La1.9Sr0.1Ni0.6Mg0.4O4 ceramic, while the loss tangent is significantly reduced by two orders of magnitude compared to the undoped La1.9Sr0.1NiO4 ceramic. The DC conductivity significantly decreased by three orders of magnitude. The giant dielectric responses are described by Maxwell-Wagner polarization and small polaron hopping mechanisms. Thus, the significant reduction in the loss tangent can be attributed to the significantly enhanced resistance of the grain boundaries.

Thermally Stable Silicone Elastomer Composites Based on MoS2@Biomass-Derived Carbon with a High Dielectric Constant and Ultralow Loss for Flexible Microwave Electronics.

With the miniaturization and integration of electronic components in wireless communication and wearable devices, the demand for low-cost flexible composites with temperature-stable high dielectric constant and low loss has substantially increased. However, such comprehensive properties are fundamentally difficult to combine for conventional conductive and ceramic composites. Here, we develop silicone elastomer (SE) composites based on hydrothermally grown MoS2 on tissue paper-derived cellulose carbon (CC). Such design promoted the formation of microcapacitors, multiple interfaces, and defects reinforcing interfacial and defect polarizations and resulting in a high dielectric constant of 9.83 at 10 GHz with low filler loading of 15 wt %. Unlike highly conductive fillers, MoS2@CC with low conductivity ensured a very low loss tangent of 7.6 × 10-3, which was also influenced by the filler dispersion and adhesion to the matrix. Apart from breaking the typical conflict between high dielectric constant and low losses of traditional conductive composites, MoS2@CC SE composites were highly flexible with temperature-stable dielectric properties making them attractive as flexible substrates in microstrip antenna applications and extreme environment electronics. Moreover, recycling from waste tissue paper makes them potential candidates as low-cost and sustainable dielectric composites.

Elucidating the combinatorial effect of substrate stiffness and surface viscoelasticity on cellular phenotype.

Cells maintain tensional homeostasis by monitoring the mechanics of their microenvironment. In order to understand this mechanotransduction phenomenon, hydrogel materials have been developed with either controllable linear elastic or viscoelastic properties. Native biological tissues, and biomaterials used for medical purposes, often have complex mechanical properties. However, due to the difficulty in completely decoupling the elastic and viscous components of hydrogel materials, the effect of complex composite materials on cellular responses has largely gone unreported. Here, we characterize a novel composite hydrogel system capable of decoupling and individually controlling both the bulk stiffness and surface viscoelasticity of the material by combining polyacrylamide (PA) gels with microgel thin films. By taking advantage of the high degree of control over stiffness offered by PA gels and viscoelasticity, in terms of surface loss tangent, of microgel thin films, it is possible to study the influence that bulk substrate stiffness and surface loss tangent have on complex fibroblast responses, including cellular and nuclear morphology and gene expression. This material system provides a facile method for investigating cellular responses to complex material mechanics with great precision and allows for a greater understanding of cellular mechanotransduction mechanisms than previously possible through current model material platforms.

Biophysical properties of hydrogels for mimicking tumor extracellular matrix.

The extracellular matrix (ECM) is an essential component of the tumor microenvironment. It plays a critical role in regulating cell-cell and cell-matrix interactions. However, there is lack of systematic and comparative studies on different widely-used ECM mimicking hydrogels and their properties, making the selection of suitable hydrogels for mimicking different in vivo conditions quite random. This study systematically evaluates the biophysical attributes of three widely used natural hydrogels (Matrigel, collagen gel and agarose gel) including complex modulus, loss tangent, diffusive permeability and pore size. A new and facile method was developed combining Critical Point Drying, Scanning Electron Microscopy imaging and a MATLAB image processing program (CSM method) for the characterization of hydrogel microstructures. This CSM method allows accurate measurement of the hydrogel pore size down to nanometer resolution. Furthermore, a microfluidic device was implemented to measure the hydrogel permeability (Pd) as a function of particle size and gel concentration. Among the three gels, collagen gel has the lowest complex modulus, medium pore size, and the highest loss tangent. Agarose gel exhibits the highest complex modulus, the lowest loss tangent and the smallest pore size. Collagen gel and Matrigel produced complex moduli close to that estimated for cancer ECM. The Pd of these hydrogels decreases significantly with the increase of particle size. By assessing different hydrogels' biophysical characteristics, this study provides valuable insights for tailoring their properties for various three-dimensional cancer models.

Effect of the Particle Size and Layer Thickness of GNP Fillers on the Dielectric Properties and Actuated Strain of GNP-PDMS Composites.

Dielectric elastomer actuators (DEAs), a type of electroactive polymers (EAPs), are smart materials that are used in various fields such as artificial muscles and biomimetic robots. In this study, graphene nanoplatelets (GNPs), which are conductive carbon fillers, were added to a widely used DEA, namely, polydimethylsiloxane (PDMS), to improve its low actuated strain. Four grades of GNPs were used: H5, H25, M5, and M25 (here, the number following the letter indicates the average particle size of the GNPs in µm). The average layer thickness of the H grade is 13−14 nm and that of the M grade is 5−7 nm. PDMS composites were prepared by adding 0.5, 1, 2, and 3 wt% of each GNP, following which the mechanical properties, dielectric properties, and actuated strain of the composites were measured. The mechanical properties were found to increase as the particle size increased. Regarding the dielectric characteristics, it was found that the higher the aspect ratio of the filler, the easier the formation of a micro-capacitor network in the composite­this led to an increase in the dielectric constant. In addition, the higher amounts of GNPs in the composites also led to an increase in the dielectric constant. For the actuated strain analysis, the electromechanical sensitivity was calculated using the ratio of the dielectric constant to the Young's modulus, which is proportional to the strain. However, it was found that when the loss tangent was high, the performance of the actuated strain decreased owing to the conversion of electric energy into thermal energy and leakage current loss. As a result, the highest actuated strain was exhibited by the M25 composite, with an actuated strain value of 3.01% measured at a low electric field (<4 kV/mm). In conclusion, we proved that the GNP−PDMS composites with a thin layer and large particle size exhibited high deformation.