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We propose a method to realize the kilogram through electrical units, namely, the volt. The device is based on a simple plane plate electrostatic actuator used to counterbalance the weight force. The geometry of the electric field is characterized by changing the distance between the plates while maintaining a constant force and measuring the capacitance. This approach leads to the realization of a simple and compact device for the absolute measurement of small masses. The preliminary results show a relative uncertainty of 10−3 for mass above 10 mg. A series of uncertainty sources has been pointed out. An improvement of one order of magnitude is expected by correcting these sources. [ABSTRACT FROM AUTHOR]

Planar and flexible climbing robots suffer from buckling while climbing on a vertical surface. This paper analyzes two different modes: one-end free buckling and two-ends fixed buckling. As an example for buckling analyses, the paper focuses on an electrostatic climbing robot that features thin body. As the body of the robot has only 2.5 mm of thickness, it is more prone to buckling than any other flexible robots, making it the best example for the buckling problem. Based on the analyses, the paper proposes a buckling-free control strategy for the electrostatic robots. The proposed strategy guarantees the force balance between adhesive force and weight force, as well as the elastic stability of the robot. To implement the strategy, the paper investigates the available region of the proper forces and optimal parameters on the prototype robot. A prototype of climbing robot was developed to verify the analyses and solutions, weighing merely 29 g (excluding battery and control circuits). It successfully climbed up a vertical wall without buckling, carrying the payload of 0.4 N. [ABSTRACT FROM PUBLISHER]

The electrostatic actuation method has not been used widely in bimorph cantilevers despite its advantage of large displacement and low power consumption, mostly owing to the fact that it is limited to just two stable positions: 1) initial curled; and 2) final flat positions. In this paper, we first demonstrate a bimorph cantilever actuator having multiple steady-state positions in between those two boundary positions, accomplished by simply dividing the bottom electrode. We found that the number of steady-state positions and the steady-state tip heights can be controlled by the design of the bottom electrode. In our test experiment, the steady-state bimorph cantilever tip heights were 48 \mu \textm at 0 V, 28 \mu \textm at 21 V, 7 \mu \textm at 25 V, and 0 \mu \textm (flat) at 29 V, respectively. In order to relieve low reliability of the electrostatic bimorph cantilever, we devised non-contact actuation method and demonstrated that the lifetime of the electrostatic bimorph actuator greatly increased. This paper will pave the way to utilize bimorph cantilever actuators with greater versatility. [2016-0081] [ABSTRACT FROM AUTHOR]

A new bistable micro-electro-mechanical systems actuator functioned by the potassium ion electret technique is presented. We utilize a three-terminal comb-drive actuator with a built-in electret potential. We first describe the operation principle of the bistable device that is driven by a pulse and/or step-function voltage. We next explain the fabrication results and the procedure of the electret polarization. Device operation is demonstrated to determine the switching characteristics from one stable state to another with a 12 V pulse voltage of 300~\mu \texts duration. We also establish bistable switching operation with a step voltage of 5 V or less, which is manageable by a battery for portable equipment. Discrepancy of switching characteristics between the theory and the experiments is discussed from a point of view on the fringe electrical fields between the comb electrodes. [2016-0079] [ABSTRACT FROM AUTHOR]

This paper demonstrates experimentally, theoretically, and numerically for the first time, a wide-range tunability of an in-plane clamped–clamped microbeam, bridge, and resonator actuated electrothermally and electrostatically. Using both actuation methods, we demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally by passing a dc current through it, and electrostatically by applying a dc polarization voltage between the microbeam and the stationary electrode. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Adding a dc bias changes the qualitative nature of the tunability both before and after buckling, which adds another independent way of tuning. This reduces the dip before buckling, and can eliminate it if desired, and further increases the fundamental frequency after buckling. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared with the experimental data and simulation results of a multi-physics finite-element model. A good agreement is found among all the results. [2015-0341] [ABSTRACT FROM PUBLISHER]

A three-degrees-of-freedom microelectromechanical systems (MEMS) electrostatic actuator was developed, fabricated, and tested. The actuator utilizes a piston-tube configuration that enables the use of electrodes with a wide area. Therefore, a large output force can be generated. The actuator also utilizes a flexure mechanism in which the in-plane ( $x$ - $y)$ stiffness is high compared with the out-of-plane ( $z$ -axis) stiffness. This flexure mechanism enables a large translation stroke along the $z$ -axis before experiencing lateral pull-in instability. A prototype of the actuator was able to achieve a pure translation (piston-style motion) of $28~\mu $ m at 80 V and an angle of rotation of 0.78° at 70 V. A mass of 1 mg was translated $24~\mu $ m at 80 V, indicating the ability of the actuator to provide high output force. The actuator was fabricated using the Micralyne MicraGEM-Si MEMS fabrication process, in which the pistons and tubes are fabricated in the device layers of two bonded Silicon on insulator (SOI) wafers. The misalignment between the pistons and the tubes using this process was $\sim 0.005$ of the gap between adjacent pistons and tubes. This amount of misalignment leads to a negligible lateral instability effect. [2014-0277] [ABSTRACT FROM AUTHOR]

To further decrease feature sizes, the semiconductor industry heavily improved the photolithography. Photoresist layers are exposed through photomasks and structured accordingly. The underlying substrate is then selectively altered by adding or subtracting material. The unrivaled precision, resolution, and accuracy allow an unmatched level of miniaturization, and several thousand electrical components can be processed simultaneously. This technology was expanded to the fabrication of sensors and actuators, creating microelectromechanical systems. With silicon, the possibilities of further expanding this technology to new dimensions and applications are limited. Reasons are the stiffness, 2.5-D fabrication, and lack of optical transparency. To enable new applications, we present the successful translation of wafer-level fabrication to millimeter-scale actuators. This was achieved by changing the material to ultraviolet (UV)-curable polymers. Based on the electrostatic zipper actuator, avoiding the common pull-in-effect is essential for the successful realization of an acceptable microactuator. Therefore, the bottom electrodes are split and shaped to adjust the generated electrostatic forces, balancing the mechanical restoring forces. Besides the theoretical design, the fabrication technology based on classic photolithography is explained. Experimental results include voltage-dependent deflection measurements, achieving 110- $\mu $ m deflection with 70 V driving voltage. The dynamic response measurements show resonance frequencies of 1.89 kHz. [2014-0181] [ABSTRACT FROM PUBLISHER]

Capacitive comb actuators are widely used as MEMS motors due to their long range of linear motion, low power consumption, and ease of fabrication. Here, we present data from a thin comb capacitive actuator where fringe fields contribute significantly to the device performance. We characterize the observed levitation effect and discuss two methods to control the out-of-plane forces: 1) by means of alternating the comb polarity; and 2) by using an additional electrode below the comb. Considering two alternative designs, it is shown how the levitation force can be mitigated. One design decreases the out-of-plane motion by a factor of two, but also reduces the lateral range. An alternative design proved successful in decreasing out-of-plane motion by 75%, while enhancing the in-plane displacement of the linear comb actuator by over 35%. [ABSTRACT FROM AUTHOR]

This paper reports the modeling and analysis of a linear resonant electrostatic induction motor, with an imbalance in capacitance taken into consideration. The motor is an asynchronous motor consisting of film-type stator and slider with three-phase electrodes, driven by three-phase voltage applied to the stator. The slider electrodes are connected to three coils, which enable the slider voltage to rise high at resonance, producing large thrust force. The motor is highly sensitive to an imbalance of capacitance, particularly at resonance. A model is developed to relate each capacitance formed among the electrodes to symmetrical components of the slider voltage and to the thrust force of the motor. The model indicated that the capacitance imbalance leads to an unbalanced slider voltage with two frequency components and causes thrust force ripple. These nonideal effects were confirmed by experiments, using a motor with geometric asymmetry in its electrode design. [ABSTRACT FROM PUBLISHER]

We present a gap-closing electrostatic actuator with a linear extended range. We achieve this by designing a nonlinear spring that exactly counteracts the nonlinear effects of electrostatic attraction forces in gap-closing actuators. We demonstrate this on parallel-plates actuators with a nominal gap of g=21~\mum. The initial response up to a deflection of g/4 is stable and is inevitably nonlinear, but beyond this point we demonstrate good linearity up to a displacement of 85% of the nominal gap. By introducing the nonlinear spring, we also avoid the pull-in instability, which would have occurred at a voltage of 31 V. Instead, the system is stable and the driving voltage may be increased up to 130 V where the maximal displacement is achieved. \hfill[2013-0132] [ABSTRACT FROM AUTHOR]

A micromachined polymer membrane-based active probe has been developed for biomolecular force spectroscopy. The probe has integrated but significantly decoupled electrostatic actuation and optical interferometric force sensing capabilities. Devices have been fabricated on silicon substrates using Parylene as the membrane material. The electrostatic actuator integrated into the probe could provide > 1-\mu\m displacement with a flat response of up to 30 kHz in fluid, a feature particularly useful in fast-pulling force spectroscopy experiments involving biomolecules. The probes were successfully employed to measure the unbinding forces between biotin and streptavidin, wherein the force noise level was <10 pN with a 1-kHz bandwidth for an 8-N/m membrane with a 25-kHz resonance frequency in fluid. This is in agreement with the thermal noise data generated by a finite-element model that predicts further improvements with simple design changes. \hfill[2010-0069] [ABSTRACT FROM PUBLISHER]