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In this paper, we present a wireless power transfer (WPT) system with a two-dimensional (2-D) magnetoinductive wave (MIW) device composed by two orthogonal sets of 1-D MIW devices woven together. The device is made by 112 double-spiral coils, a geometry that we have optimized to render a low attenuation propagation. This approach enables a charging area of 22 × 22 cm2 from which a receiver device can be supplied with energy with optimum efficiency from 32 different locations with the use of a single excitation port. We present a detailed optimization of the design and fabrication of the device. To describe the behavior of the device, we use a modeling method based on the impedance matrix that allows us to include all coupling interactions among the increased number of cells. With this method, we are able to find the optimal operating conditions like the location of the excitation and the coupling conditions of the receiver device. With the proposed 2-D MIW device, we can provide up to 5 W to a load of 5  $\Omega$  located at the optimal axial separation. We corroborate our calculations with vector network analysis and dc output power measurements. Furthermore, we demonstrate the device supplying to distinct types of loads simultaneously. This paper is accompanied by a supplementary file showing the required MATLAB script and input files to calculate the mutual inductance between a receiver and the cells of the pad. [ABSTRACT FROM AUTHOR]

This work presents an analytic model based on the impedance matrix that can predict the transferred energy to a movable receiver device in the near field of a magnetoinductive wave transmitter array. The formulas we present apply to any resonator geometry that can be described as a set of horizontal and vertical segments. The model accurately describes the system efficiency with respect to the operating frequency and to less constraining spatial configurations of the receiver device. The formulated expressions can be easily applied to distinct wireless power transfer system configurations, such as a single pair or an array of resonators, regardless their configuration. We demonstrate that the spatial resolution of the efficiency calculation is limited when only the first coupling order between the receiver and the transmitter array is considered. However, high resolution is possible when first and second coupling orders are included. Additionally, we show that the model foresees the terminating impedance modulation schemes that we applied only after evaluation of data obtained experimentally. These modulation schemes prevent the receiver from standing above a power null resulting from the interaction of forward and backward traveling waves, one of the major challenges in traveling wave based wireless power transfer devices. [ABSTRACT FROM AUTHOR]

We present a straightforward and yet, effective method to modulate the termination impedance of 1-D $LC$ resonating arrays for wireless power applications. The modulation method is based on activating/deactivating the last two cells of the array allowing to remove the power nulls caused by standing waves inside this type of arrays. The modulation of the terminating impedances is done at a distinct frequency than the resonance frequency of the cells. We explain why and how this distinct frequency was chosen. We further demonstrate how the same modulation is applicable for a wide range of load resistances on the receiver device. Modulation is achieved by wirelessly sensing the voltage delivered by the power supply according to where above the array a receiver device is located. A microcontroller records these voltages and determines which terminating impedance will provide the highest possible efficiency to the receiver device. Changes in the terminating impedances are set by digitally controlled solid state relays. The proposed modulation method permitted to power up a receiver device with a system efficiency of up to 60% anywhere over the 30 cm length of the resonating array. [ABSTRACT FROM PUBLISHER]

In this paper, a model of Micromachined Levitated Gyroscope (MLG) with a closed-loop control is developed. The model provides a fundamental theoretical description of the operating principle of the MLG. Employing the obtained model, different operating modes of the MLG, which are depended on relationships between the speed of the rotor rotation, value of the stiffness provided by a contactless suspension and the rotor shape are considered. In particular, it is showed that decreasing the stiffness of the contactless suspension leads to two operating modes of the gyroscope, which are defined by the rotor shape. Moreover, an error model of the MLG for a closed loop is obtained, which allows us to give an explanation of the error-producing mechanics of the inherent errors of the MLG. [ABSTRACT FROM PUBLISHER]

We address the miniaturization of power converters by introducing novel 3-D microtransformers with magnetic core for low-megahertz frequency applications. The core is fabricated by lamination and microstructuring of Metglas 2714A magnetic alloy. The solenoids of the microtransformers are wound around the core using a ball-wedge wirebonder. The wirebonding process is fast, allowing the fabrication of solenoids with up to 40 turns in 10 s. The fabricated devices yield the high inductance per unit volume of 2.95 μH/mm3 and energy per unit volume of 133 nJ/mm3 at the frequency of 1 MHz. The power efficiency of 64–76% is measured for different turns ratio with coupling factors as high as 98%. To demonstrate the applicability of our passive components, two PWM controllers were selected to implement an isolated and a nonisolated switch-mode power supply. The isolated converter operates with overall efficiency of 55% and maximum output power of 136 mW; then, we experimentally demonstrate how we increased this efficiency to 71% and output power to 408 mW. The nonisolated converter can deliver an overall efficiency of 81% with a maximum output power of 515 mW. Finally, we benchmarked the results to underline the potential of the technology for power on-chip applications. [ABSTRACT FROM AUTHOR]

An analysis method used to choose a suitable structural orientation layout for a microcompliant mechanism, which includes multi-curved-beams, is introduced, particularly, for fabricating microelectromechanical-systems (MEMS) thin-curved-beam microstructures on (100) and (111) single-crystal silicon (SCS) wafers. The achievement of a large deflection of a fabricated SCS device verifies the usability of this design rule. The orientation layouts of the device for a large deflection are restricted to a specific region. Based on the analysis method, it is better to follow a 21° safe region between the <100> and <110> orientations in order to decrease the possibility of crystal slip failure. Using this design consideration, one can design more robust MEMS compliant mechanisms from SCS, exploiting its ideal elasticity. [ABSTRACT FROM AUTHOR]

This paper presents a novel combdrive configuration of a linear magnetic microactuator. We discuss in detail the influence of the air-gap geometry on the plunger motion and give design rules to avoid pull-in behavior. This analysis results in a new configuration, which is, so far, only known for electrostatic actuators. The magnetic flux is guided over several interdigitating comb structures with moderate large gap width of 25 µm instead of one single plunger, as reported for earlier designs. This results in larger forces, scaling with the number of comb fingers, until the material reaches saturation. The new configuration linearizes the characteristics and saves driving power without sacrificing fabrication stability, which would arise from small air-gap widths. Several combdrive actuators featuring one, two, and eight comb fingers were fabricated in LIGA technology, simulated, and tested. For a driving current of 40 mA, the achievable stroke is measured to increase by 800% for eight comb fingers in comparison to one finger. Alternatively, for a given stroke, a reduction of the driving current of more than 50% is measured. [ABSTRACT FROM AUTHOR]

In this letter, we present a new hybrid micromachined contactless suspension based on combining electromagnetic inductive and electrostatic actuation. In addition, the stiffness components are dynamically adjusted during the operation phase using a series of electrodes integrated in the contactless suspension structure. We experimentally demonstrate vertical linear positioning of a disk-shaped proof mass in a range from 30 to 200~\mathrm \mathbf \mu m , controlled tilting about two orthogonal axes in the horizontal plane ranges from ±1° to ±4°, as well as controlled oscillation about the vertical axis with an angular displacement of 37° at a frequency of 1.5 Hz. In order to demonstrate dynamical adjustment of the stiffness, we experimentally show that the angular component of stiffness is increased by a factor of two at a levitation height of 100 \mathrm \mathbf \mu m . Therefore, the suspension dynamics can be changed and adapted to particular applications or to variations in operational environments. Moreover, we demonstrate that this device can operate as a bistable micro-actuator. [2015-0150] [ABSTRACT FROM PUBLISHER]