Effect Of Dielectric Layer Thickness Research Articles

A triboelectric nanogenerator coupled with internal and external friction for gesture recognition based on EHD printing technology

Surface charge density is a critical factor in determining the output performance of triboelectric nanogenerators (TENGs). However, enhancing the surface charge density is a relatively complex process characterized by high cost, fast charge dissipation, and inferior stability. Herein, a TENG with internal and external friction synergistic coupling enhancement that employed an electrohydrodynamic (EHD) printing technique for gesture recognition was proposed. Under the external force, the electrical performance of the triboelectric material could be improved via internal friction formed by the contact between the lines of silver nanowires (AgNWs) mixing with hydroxy propyl methyl cellulose (HPMC) (AgNWs (HPMC)) inside the tribolayer and the PDMS with microgrooves. The effects of dielectric layer thickness, micropore size, the number of micropore arrays, as well as the AgNWs content and the number of AgNWs (HPMC) lines on TENG output performance were analysed systematically. When the micropore arrays TENG (MA-TENG) size was 15 mm × 15 mm, the thickness of a dielectric layer was 240 µm, the number of micropore arrays was 36, and the number of AgNWs (HPMC) lines was 28, the charge transfer quantum of MA-TENG was 34.9 nC, which is about 5.8 times that of flat TENG. The peak power of the MA-TENG was 580 μW, which was about 10 times than that of the flat TENG. Finally, a self-powered gesture recognition was demonstrated successfully based on the developed MA-TENG and revealed its potential in the field of human-computer interaction. This work not only proposed a new method with the advantages of a simple process, low cost, and high output stability, to significantly increase the surface charge density, but also provided a new scheme for electronic skin and wearable devices.

Experimental study on the effects of dielectric layer thickness and elastic modulus on the performance of flexible capacitive sensor films

Experimental study on the effects of dielectric layer thickness and elastic modulus on the performance of flexible capacitive sensor films

Rationally Designed Dual‐Mode Triboelectric Nanogenerator for Harvesting Mechanical Energy by Both Electrostatic Induction and Dielectric Breakdown Effects

AbstractWith the advantages of its light weight, low cost, and high efficiency especially at low operation frequency, the triboelectric nanogenerator (TENG) is considered to be a potential solution for self‐powered sensor networks and large‐scale renewable blue energy. However, the conventional TENG converts mechanical energy into electrical energy only via either electrostatic induction or electrostatic breakdown. Here, a novel dual‐mode TENG is presented, which can simultaneously harvest mechanical energy by electrostatic induction and dielectric breakdown in a single device. Based on the complementary working mechanism, it achieves a great improvement in the output performance with the sum of two TENGs via a single mechanism and reveals the effect of dielectric layer thickness on the triboelectrification, electrostatic induction, and air breakdown. This study establishes a new methodology to optimize TENGs and provides a new tool to investigate the triboelectrification, electrostatic induction and dielectric breakdown simultaneously.

Analysis of Pull-in Voltage with Respect to Changes in Dielectric Material and their Thickness

Micro Electromechanical Systems (MEMS) actuators experience pull-in effect in their actuation range. MEMS actuating elements are thin parallel plate capacitor electrodes separated with air gap. Parallel plate electrostatic micro actuators are known to have the pull-in effect, where electrostatic attractive force exceeds the mechanical restoring force of the suspending spring, and that the movable plate spontaneously pulled into physical contact with the opposite electrode. In our model the effect of dielectric layer thickness is taken into account for predicting the pull-in voltage. The critical role of different dielectric layer materials in bringing down the static pull-in voltage is verified by using COMSOL.

Dendritic wideband metamaterial absorber based on resistance film

A type of dendritic wideband metamaterial absorber was designed and constructed from resistance film composed of indium-tin oxide conductive film having a dendritic metamaterial structure, dielectric layer made of polymethacrylimide foam, and metallic sheet based on the equivalent circuit model. In terms of normal incidence, the simulation using the absorber yielded operating absorption rates >80 % in the frequency range of 8–27.9 GHz. In addition, the experimental measurements verified 8–17 GHz range of more than 80 % absorption rate, whereas its relative bandwidth reached 72 %. Moreover, this reasonable absorption performance was maintained for oblique incidences of <60°. The effects of dielectric layer thickness on absorption properties were verified.

NUMERICAL STUDY OF DIELECTROPHORESIS FORCE IN THE ISOLATED ELECTRODE: A COMPARATIVE APPROACH

One of the general methods for particle separation in lab-on-a-chips (LOCs) is dielectrophoresis (DEP). The effects of electrode isolation in DEP-based particle separation devices are discussed throughout this paper. One advantage of the electrode isolation is reducing electrode–electrolyte–sample mutual interactions. In this study, the conventional DEP forces using interdigitated electrode arrays is numerically investigated without and in the presence dielectric layer in the interface of electrode and electrolytic fluid. The study includes the effect of dielectric layer thickness when fluids of different electrical conductivity are involved. The results show that the electric field and also intra-channel gradient of electric field square depend on frequency and an isolating layer acts as high-pass filter, thus frequency response of conventional DEP force besides Clausius–Mossotti (CM) factor is depended on the electric field gradient. The results also show that in contactless model, the frequency response of the DEP forces can be engineered by dielectric thickness and electrical conductivity of the suspending medium. According to the obtained results, during particle separation with DEP method in the presence of insolated electrodes and considering the reduction in electric field intensity, an appropriate and optimal choice for working frequency, voltage of electrodes and thickness of dielectric layer should be considered. The particles and dielectric isolated layer under study is polystyrene beads and polydimethylsiloxane (PDMS) elastomeric polymer, respectively.

Optimization of the Dielectric Layer Thickness for Surface-Plasmon-Induced Light Absorption for Silicon Solar Cells

In this study, we investigate the effect of dielectric layer thickness on light reflection due to random self-assembled Ag nanoparticles with diameters of less than 160 nm deposited on the Si substrate, indicating that a dielectric layer with an appropriate thickness is useful for reducing the amount of reflected light. In the short wavelength range, reflectivity is determined by the metallic plasmon and the SiO2 antireflection layer, and the effect of the surface plasmon dominates over the antireflection effect. In the long wavelength range, reflectivity decreases with increasing dielectric layer thickness and is determined by the oxide antireflection layer, while the effect of the surface plasmon is negligibly small. Moreover, the surface plasmon is affected by the SiO2 layer and Si substrate when the dielectric layer is thin; however, it is only determined by the SiO2 layer when the oxide layer is sufficiently thick. These observations have substantial applications for the optimization of surface-plasmon-enhanced silicon solar cells.

Optimization of the Dielectric Layer Thickness for Surface-Plasmon-Induced Light Absorption for Silicon Solar Cells

In this study, we investigate the effect of dielectric layer thickness on light reflection due to random self-assembled Ag nanoparticles with diameters of less than 160 nm deposited on the Si substrate, indicating that a dielectric layer with an appropriate thickness is useful for reducing the amount of reflected light. In the short wavelength range, reflectivity is determined by the metallic plasmon and the SiO2 antireflection layer, and the effect of the surface plasmon dominates over the antireflection effect. In the long wavelength range, reflectivity decreases with increasing dielectric layer thickness and is determined by the oxide antireflection layer, while the effect of the surface plasmon is negligibly small. Moreover, the surface plasmon is affected by the SiO2 layer and Si substrate when the dielectric layer is thin; however, it is only determined by the SiO2 layer when the oxide layer is sufficiently thick. These observations have substantial applications for the optimization of surface-plasmon-enhanced silicon solar cells.

Study on the interaction between a sheet electron beam and the slow-wave structure for dielectric-loaded rectangular Cerenkov maser

A three-dimensional model for the interaction between a sheet electron beam and the slow-wave structure of dielectric-loaded rectangular Cerenkov maser is proposed. Based on this model, the hybrid-mode dispersion equation and its analytical solution are derived by using the field-match method and the Borgnis function method. Through numerical calculations, the effects of dielectric layer thickness, beam voltage, current density, bean thickness and beam-dielectric layer gap on the linear growth rate are analyzed.

Enhanced electrical and photosensing properties of pentacene organic thin-film phototransistors by modifying the gate dielectric thickness

The effects of dielectric layer thickness on the electrical performance and photosensing properties of organic pentacene thin-film transistors have been investigated. To improve the electrical performance of pentacene thin-film transistors (TFTs), the poly-4-vinylphenol (PVP) polymer with various thicknesses was used in fabrication of the pentacene transistors. The pentacene thin-film transistor with the PVP dielectric layer of 70 nm exhibited a field-effect mobility of 4.46 cm 2/Vs in the saturation region, a threshold voltage of −4.0 V, a gate voltage swing of 2.1 V/decade and an on/off current ratio of 5.1 × 10 4. In the OFF-state, the photoresponse of the transistors increases linearly with illumination intensity. The pentacene transistor with the thinner dielectric layer thickness indicates the best photosensing behavior. It is evaluated that the electrical performance and photosensing properties of pentacene thin-film transistors can be improved by using various thickness dielectric layer.

Influence of lattice parameters on the resonance frequencies of a cut-wire-pair medium

We studied both theoretically and experimentally the influence of the lattice constant on the resonance frequencies of cut-wire-pair structures, which are essential components in assembling left-handed materials. These structures were designed and fabricated, and the transmission spectra were measured in the microwave-frequency regime. Numerical simulation was performed using the transfer-matrix method. All the numerical results were in good agreement with the experimental data. It was found that the lattice parameters of the cut-wire-pair structure provide sensitive effects on the electric resonance, especially, in the propagation k and the electric field E directions, while the magnetic resonance frequency is nearly unchanged, except for its bandwidth and depth. In addition, we also studied the effect of dielectric layer thickness on the resonance frequencies of the cut-wire-pair structure. These sensitive changes in the electric resonance might have remarkable effects on the effective plasma frequency and therefore on the left-handed behavior of combined structures consisting of cut-wire pairs and continuous wires.