Gal deBotton

Bio: Gal deBotton is an academic researcher from Ben-Gurion University of the Negev. The author has contributed to research in topics: Dielectric elastomers & Dielectric. The author has an hindex of 30, co-authored 77 publications receiving 2311 citations. Previous affiliations of Gal deBotton include California Institute of Technology & University of Pennsylvania.

All-organic dielectric-percolative three-component composite materials with high electromechanical response

Abstract: By combining the high-dielectric copper phthalocyanine oligomer (PolyCuPc) and conductive polyanline (PANI) within polyurethane (PU) matrix an all-organic three-component dielectric-percolative composite with high dielectric constant is demonstrated. In this three-component composite system, the high-dielectric-constant PolyCuPc particulates enhance the dielectric constant of the PU matrix and this combined two-component dielectric matrix in turn serves as the high-dielectric-constant host for the PANI to realize percolative phenomenon and further enhance the dielectric response. As a result, an electromechanical strain of 9.3% and elastic energy density of 0.4 J/cm(3) under an electric field of 20 V/mum can be induced.

Stress-driven collagen fiber remodeling in arterial walls.

Abstract: A stress-driven model for the relation between the collagen morphology and the loading conditions in arterial walls is proposed We assume that the two families of collagen fibers in arterial walls are aligned along preferred directions, located between the directions of the two maximal principal stresses For the determination of these directions an iterative finite element based procedure is developed As an example the remodeling of a section of a human common carotid artery is simulated We find that the predicted fiber morphology correlates well with experimental observations Interesting outcomes of the model including local shear minimization and the possibility of axial compressions due to high blood pressure are revealed and discussed

Neo-Hookean fiber-reinforced composites in finite elasticity

Abstract: The response of a transversely isotropic fiber-reinforced composite made out of two incompressible neo-Hookean phases undergoing finite deformations is considered. An expression for the effective energy–density function of the composite in terms of the properties of the phases and their spatial distribution is developed. For the out-of-plane shear and extension modes this expression is based on an exact solution for the class of composite cylinder assemblages. To account for the in-plane shear mode we incorporate an exact result that was recently obtained for a special class of transversely isotropic composites. In the limit of small deformation elasticity the expression for the effective behavior agrees with the well-known Hashin–Shtrikman bounds. The predictions of the proposed constitutive model are compared with corresponding numerical simulation of a composite with a hexagonal unit cell. It is demonstrated that the proposed model accurately captures the overall response of the periodic composite under any general loading modes.

Snap-through actuation of thick-wall electroactive balloons

Abstract: Solution to the problem of a spherical balloon made out of an electroactive polymer which is subjected to coupled mechanical and electrical excitations is determined. It is found that for certain material behaviors instabilities that correspond to abrupt changes in the balloon size can be triggered. This can be exploited to electrically control different actuation cycles as well as to use the balloon as a micro-pump.

Dielectric elastomer composites

Abstract: The coupled electromechanical response of electroactive dielectric composites is examined in the setting of small deformation and moderate electric field In this setting, the mechanical stress depends quadratically on the electric field through a combination of material electrostriction and Maxwell stress It is rigorously shown that the macroscopic mechanical stress of the composite also depends quadratically on the macroscopic electric field It is further demonstrated that the effective electromechanical coupling can be computed from the examination of the uncoupled electrostatic and elastic problems The resulting expressions suggest that the effective electromechanical coupling may be very large for microstructures that lead to significant fluctuations of the electric field This idea is explored through examples involving sequential laminates It is demonstrated that the electromechanical coupling – the macroscopic strain induced in the composite through the application of a unit electric field – can be amplified by many orders of magnitude by either a combination of constituent materials with high contrast or by making a highly complex and polydisperse microstructure These findings suggest a path forward for overcoming the main limitation hindering the development of electroactive polymers

Advances in dielectric elastomers for actuators and artificial muscles.

Abstract: A number of materials have been explored for their use as artificial muscles Among these, dielectric elastomers (DEs) appear to provide the best combination of properties for true muscle-like actuation DEs behave as compliant capacitors, expanding in area and shrinking in thickness when a voltage is applied Materials combining very high energy densities, strains, and efficiencies have been known for some time To date, however, the widespread adoption of DEs has been hindered by premature breakdown and the requirement for high voltages and bulky support frames Recent advances seem poised to remove these restrictions and allow for the production of highly reliable, high-performance transducers for artificial muscle applications

Gate Dielectrics for Organic Field‐Effect Transistors: New Opportunities for Organic Electronics

Abstract: In this contribution we review the motivations for, and recent advances in, new gate dielectric materials for incorporation into organic thin-film transistors (OTFTs) for organic electronics. After a general introduction to OTFT materials, operating principles, and processing requirements for optimizing low-cost organic electronics, this review focuses on three classes of OTFT-compatible dielectrics: i) inorganic (high-k) materials; ii) polymeric materials; and iii) self-assembled mono- and/multilayer materials. The principal goals in this active research area are tunable and reduced OTFT operating voltages, leading to decreased device power consumption while providing excellent dielectric/insulator properties and efficient low-cost solution-phase processing characteristics.

Physical Properties of Composites Near Percolation

Abstract: Dramatic changes in the physical properties of composites occur when filler particles form a percolating network through the composite, particularly when the difference between the properties of the constitutive phases is large. By use of electric conductivity and dielectric properties as examples, recent studies on the physical properties of composites near percolation are reviewed. The effects of geometric factors and intrinsic properties of the fillers and the matrix, and especially of the interface between fillers and matrix, on electric and dielectric properties near percolation are discussed. Contact resistivity at the interface is less desirable for enhancing electrical conductivity. By contrast, an interface with high resistivity suppresses tunneling between adjacent fillers and leads to percolative composites with higher dielectric constant but lower dielectric loss. This review concludes with an outlook on the future possibilities and scientific challenges in the field.

Polymer Composite and Nanocomposite Dielectric Materials for Pulse Power Energy Storage

Abstract: This review summarizes the current state of polymer composites used as dielectric materials for energy storage The particular focus is on materials: polymers serving as the matrix, inorganic fillers used to increase the effective dielectric constant, and various recent investigations of functionalization of metal oxide fillers to improve compatibility with polymers We review the recent literature focused on the dielectric characterization of composites, specifically the measurement of dielectric permittivity and breakdown field strength Special attention is given to the analysis of the energy density of polymer composite materials and how the functionalization of the inorganic filler affects the energy density of polymer composite dielectric materials