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This study demonstrates an energy harvester that combines a piezoelectric nanogenerator and an electret-based electrostatic generator. The device consists of an in-house fabricated nanocomposite (polydimethylsiloxane/barium titanate/carbon nanotube) as a piezoelectric layer and a monocharged Teflon fluorinated ethylene propylene as an electret electrostatic layer. The mechanical impedance of the structure can be altered easily by changing the nanocomposite monomer/cross-linker ratio and optimizing various mechanical energy sources. The energy harvester's performance was characterized by performing measurements with different frequencies (5–20 Hz) under applied dynamic loading. A total volumetric power density of ∼8.8 μW cm−3 and a total stored energy of ∼50.2 μJ min−1 were obtained. These findings indicate that this versatile, lightweight, and low-cost energy harvester can be employed as a power supply source for microelectronics in applications, such as wearables. [ABSTRACT FROM AUTHOR]

The electrostatic acceleration of helicon plasma is investigated using an electrostatic potential exerted between the ring anode at the helicon source exit and an off-axis hollow cathode in the downstream region. In the downstream region, the magnetic field for the helicon source, which is generated by a solenoid coil, is modified using permanent magnets and a yoke, forming an almost magnetic field-free region surrounded by an annular cusp field. Using a retarding potential analyzer, two primary ion energy peaks, where the lower peak corresponds to the space potential and the higher one to the ion beam, are detected in the field-free region. Using argon as the working gas with a helicon power of 1.5 kW and a mass flow rate of 0.21 mg/s, the ion beam energy is on the order of the applied acceleration voltage. In particular, with an acceleration voltage lower than 150 V, the ion beam energy even exceeds the applied acceleration voltage by an amount on the order of the electron thermal energy at the exit of the helicon plasma source. The ion beam energy profile strongly depends on the helicon power and the applied acceleration voltage. Since by this method the whole working gas from the helicon plasma source can, in principle, be accelerated, this device can be applied as a noble electrostatic thruster for space propulsion. [ABSTRACT FROM AUTHOR]

We recently developed a method to directly actuate a cantilever in aqueous solutions by electrostatic force [K.-I. Umeda et al., Appl. Phys. Express 3, 065205 (2010)]. However, the cantilever was actuated by surface stress in a low frequency regime. We solved this problem by applying amplitude-modulated high-frequency electric fields, which actuates the cantilever solely by electrostatic force. The time variations of the self-oscillation frequency of a cantilever and the Au(111) surface images by frequency-modulation atomic force microscopy using acoustic, photothermal, and the improved electrostatic actuation methods were compared, which demonstrates the advantages of the last method such as stability and simplicity in instrumentation. [ABSTRACT FROM AUTHOR]

Vertical electrostatic wedge actuators are described that control nanometer-scale gaps between surfaces. Standard parallel-plate electrostatic actuators become difficult to stabilize across extremely small gaps because the nature of the forces and the force laws that describe them often deviate from a Coulomb's law dependence. In this work, a nanometer-scale air gap between a collapsed cantilever structure formed by two facing In0.53Ga0.47As surfaces, with areas of tens of microns, was controlled by a wedge electrostatic actuator. Upon actuation, the gap spacing between the surfaces was tuned over a maximum range of 55 nm with an applied voltage of 60 V. [ABSTRACT FROM AUTHOR]

We report on the electrolytic gating of α-sexithiophene thin film transistors, in which the organic semiconductor is in direct contact with an electrolyte. Due to the large capacitance of the electrical double layer at the electrolyte/semiconductor interface, modulation of the channel conductivity via an electrical field effect is achieved at low voltages. The transistors are stable for several hours and are sensitive to variations in the pH resulting from a pH-dependent surface charge, which modulates the threshold voltage. The response to different ion concentrations is described by the influence of the ions on the mobility and an electrostatic screening effect. [ABSTRACT FROM AUTHOR]

We present an electromechanical stability analysis of passivated parallel-plate electrostatic actuators in conductive dielectric media and show that the pull-in instability can be eliminated by tuning the applied frequency below a design-dependent stability limit. A partial instability region is also obtained, where the actuator jumps from the pull-in displacement to another stable position within the gap. The results predict that the stability limit is always greater than the critical actuation frequency, and therefore any device that is feasible to actuate in a conductive fluid can be operated with stability over the full range of motion. [ABSTRACT FROM AUTHOR]

The mechanism of flatband voltage roll-off (FVRO) has been investigated with capacitors fabricated on terraced oxide with various thicknesses of Al2O3 film deposited by atomic layer deposition. It is found that the FVRO is mainly controlled by the thickness of the bottom interfacial layer and is independent of Al2O3 thickness. This indicates that the dipole at the SiO2/Al2O3 interface is mainly responsible for the FVRO phenomenon rather than the charges. Electrostatic analysis suggests that the disruption of the interface dipole by oxygen vacancy generated in thinner bottom interfacial layer is a potential cause of the FVRO. [ABSTRACT FROM AUTHOR]

The effect of conducting pipes on the equilibrium of intense nonaxisymmetric continuous beams of charged particles is investigated. For a cylindrical pipe and an elliptical beam, we obtain an exact closed form analytical expression for the electrostatic potential. Using a variational principle, we then explore the distortions that equilibrium beams suffer due to the conducting channel. Finally, we present an exact proof that despite the nonlinear forces acting on beams of arbitrary cross section inside conducting pipes of arbitrary shape, the density of these beams remains homogeneous and their cross sectional area remains the same as the one in free space. [ABSTRACT FROM AUTHOR]

We electrostatically placed a single ferritin molecule on a nanometric 3-aminopropyltriethoxysilane (APTES) pattern that was on an oxidized Si substrate. The numerical analysis of the total interaction free energy for ferritin predicted that a quadrilateral array of 15 nm diameter APTES nanodisks placed at intervals of 100 nm would accommodate a single molecule of ferritin in each disk under a Debye length of 14 nm. The experiments we conducted conformed to theoretical predictions and we successfully placed a single ferritin molecule on each ATPES disk without ferritin adsorbing on the SiO2 substrate surface. [ABSTRACT FROM AUTHOR]

First-principles density functional calculations are employed to study the (001) surface of BaZrO3 with both BaO and ZrO2 termination. Surface structure and band structure have been obtained. For the ZrO2-terminated surface, the large displacement of the O atoms in the first layer results in the small surface rumpling. In addition, the largest relaxation appears on the second layer atoms but not on the very first layer ones. The analysis of the structure relaxation parameters reveals that the rumpling of the (001) surface for BaZrO3 with the BaO termination is stronger than that of BaTiO3. The origin of the different surface relaxation behavior between the two materials is discussed. The surface state appears in the band structure of the ZrO2-terminated surface of BaZrO3. [ABSTRACT FROM AUTHOR]

First-principles density functional calculations are employed to study the (001) surface of BaZrO3 with both BaO and ZrO2 termination. Surface structure and band structure have been obtained. For the ZrO2-terminated surface, the large displacement of the O atoms in the first layer results in the small surface rumpling. In addition, the largest relaxation appears on the second layer atoms but not on the very first layer ones. The analysis of the structure relaxation parameters reveals that the rumpling of the (001) surface for BaZrO3 with the BaO termination is stronger than that of BaTiO3. The origin of the different surface relaxation behavior between the two materials is discussed. The surface state appears in the band structure of the ZrO2-terminated surface of BaZrO3. [ABSTRACT FROM AUTHOR]

A correction to the article "Electrostatic driven collapsible Au thin films assembled using transfer printing for thermal switching" that was published in the 2012 issue is presented.