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This paper describes the design, fabrication and performance of a reusable ionogel-based photo-actuator, in-situ photopolymerised into a lab-on-a-disc microfluidic device, for flow control. The ionogel provides an effective barrier to liquids during storage of reagents and spinning of the disc. A simple LED (white light) triggers actuation of the ionogel for selective and precise channel opening at a desired location and time. The mechanism of actuation is reversible, and regeneration of the actuator is possible with an acid chloride solution. In order to achieve regeneration, the Lab-on-a-Disc device was designed with a microchannel connected perpendicularly to the bottom of the ionogel actuator (regeneration channel). This configuration allows the acid solution to reach the actuator, independently from the main channel, which initiates ionogel swelling and main channel closure, and thereby enables reusability of the whole device. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the electro-mechanical behaviour of a thick, laminated actuator with piezoelectric and isotropic lamina under externally applied electric loading using a new two-dimensional computational model. The elastic core is relatively thick and thus it is modelled by Timoshenko thick-beam theory. Although the piezoelectric lamina is a beam-like layer, it is formulated via a two-dimensional model because of not only the strong electro-mechanical coupling, but also of the presence of a two-dimensional electric field. It is shown in this paper that a one-dimensional model for the piezoelectric beam-like layer is inadequate. The piezoelectric model is constructed within the scope of linear piezoelectricity. The actuation response is induced through the application of external electric voltage. Under the strong coupling of elasticity and electricity, the strain energy and work of electric potential are presented. The electro-mechanical response of the laminated Timoshenko beam is formulated and determined via a variational energy principle. Numerical examples presented illustrate convincing comparison with finite element solutions and existing published data. New numerical solutions are also presented to investigate the geometric effect on the electro-mechanical bending behaviour. [Copyright &y& Elsevier]

This paper will present the development of an innovative actuator using a shape memory alloy (SMA) that is powered by available radiant energy in the space environment. Currently, self-contained or tethered power supplies provide the energy source for actuators in space applications. These can be costly, heavy and require regular maintenance and/or refueling. Ideally an actuator for space applications should have a high power density, be able to operate with little interference from its power source and maintain a low operating cost. Shape memory alloys are materials that recover internal strain with the addition of heat, thus changing thermal energy to mechanical energy. Because of this, they are known as thermomechanical motors. These materials can be thermally actuated by a number of means with the primary conventional approach based on resistive heating. Radiant energy, while typically impractical for use under normal circumstances, is a significant and abundant energy source in space and can be directed to control phase transition in a SMA material. This paper will describe the development of a radiant-heat driven SMA actuator, presenting a simple actuator model and prototype. The paper will also compare this actuator against other SMA-based actuators. [Copyright &y& Elsevier]

Abstract: Optical disc drives (ODDs) such as CD, DVD and HD-DVD are cheaper and more distributable than solid-state memories and hard disc drives (HDDs). In the era of mobile environment, ultra-slim ODDs have been studied and developed to show the feasibility of mobile application. This paper is a study on miniaturization of an optical pickup actuator, one of key components for ultra-slim ODDs. A newly configured actuator which is targeted to be installed in 5mm height ODDs is presented in this work. In order to reduce the height of the optical pickup actuator, a novel structure of suspension is developed by arranging Ω-shaped plate-suspension at both sides of a moving part in same plane. Also, the reduction of unwanted resonance peak, which is one of main issues in optical pickup actuators, is attempted. The presented structure of suspension is optimized by finite element analysis in terms of linearity and damping characteristic that reduces the unwanted resonance such as the rolling, pitching modes. The electromagnetic circuits, which generate driving forces, are arranged for high sensitivity and the reduction of the unwanted resonances. Developed actuator is tested to confirm stable frequency response characteristics in focusing and tracking directions as well as low tilt characteristics. In addition, the actuator is mounted on a DVD pickup system and optical signal from this optical pickup is detected. This reveals the feasibility as an information storage for mobile devices. [Copyright &y& Elsevier]

Abstract: This paper presents a new technique of actuating a parallel platform manipulator using shape memory alloy (SMA). This is a type of smart materials that can attain a high strength-to-weight ratio, which makes them ideal for miniature application. The work is mainly to develop a new SMA actuator and then incorporating the actuator in building the parallel manipulator prototype. The SMA used in this study is a commercial NiTi wire. The SMA wire provides an actuating force that produces a large bending and end displacement. A 3-UPU (universal–prismatic–universal) parallel manipulator using linear SMA actuators was developed. The manipulator consists of a fixed platform, a moving platform and three SMA actuators. The manipulator workspace was specified based on the restrictions due to actuator strokes and joint angle limits. System identification techniques were used to model both heating and cooling processes. An ON/OFF control was performed and the results showed closeness in simulation and experimental results. This study showed that shape memory alloy actuated beam can successfully be used to provide linear displacement. The built prototype indicates the feasibility of using SMA actuators in parallel manipulators. [Copyright &y& Elsevier]

Abstract: Several advanced technologies are introduced in automotive applications. Higher energy density and dynamic performance are demanding new and cost-effective actuator structures. Magnetostriction (MS), change in shape of materials under the influence of an external magnetic field, is one of the advanced technologies. Good understanding of specific design constrains is required to define and optimize a magnetostrictive actuator. This paper presents parametrical analysis with magnetic simulation of a magnetostrictive actuator. Proposed actuator has been designed, and the performance has been evaluated on experimental rig. Strain, elongation of the shaft, of 1000ppm at 10A and a blocked force over 4500N has been achieved with shaft of 8mm diameter, made of Terfenol-D. Furthermore, the effect of pre-stress of the Terfenol-D shaft has been evaluated experimentally. The study shows that excellent features can be obtained by magnetostrictive materials for many advanced applications. [Copyright &y& Elsevier]

Abstract: This paper describes the design and ANSYS modeling of a bidirectional thermal inchworm MEMS actuator featuring high actuation resolution (0.1μm) combined with large driving force (100mN) and power-free latching. A promising application of this device is for precision in-package positioning of optical fibers, but the actuator also has potential for wider use. The inchworm mechanism includes two E-shaped metallic actuators facing each other and a pusher between them that couples to a moveable object such as an optical fiber. Nickel is chosen as the material of the actuators due to its desirable electrical, thermal, and mechanical properties, and availability in fabrication facilities. Electrothermal actuation is used to move the pusher as well as the optical fiber in the desired direction by inputting electric currents in a particular sequence. A transient thermal–mechanical analysis shows the feasibility of the input sequence that drives the inchworm actuation. [Copyright &y& Elsevier]

Abstract: Nonlinear vibrations of piezoelectric/elastic/piezoelectric sandwich beams submitted to active control are studied in this paper. The proportional and derivative potential feedback controls via sensor and actuator layers are used. Harmonic balance method and the Galerkin procedure are adopted. A complex amplitude equation governed by two complex parameters is derived accounting for the geometric nonlinearity and piezoelectric effects. The nonlinear frequency and loss-factor amplitude relationships with respect to the gain parameters are obtained. The feedback effects are analyzed for small and large vibration amplitudes of sandwich beams. The frequency response curves are presented and discussed for various gain parameters. [Copyright &y& Elsevier]

Abstract: The paper reports on extensive experimental work for the characterization of a dielectric elastomer used as base material for electroactive polymer (EAP) actuators. The mechanical behavior of the acrylic elastomer VHB 4910 is characterized using large strain experiments (uniaxial and equibiaxial deformation) under force and displacement controlled loading conditions. Next to tensile and relaxation tests, experiments were conducted also using the so-called circular actuators. Over 40 actuators were produced (with different in-plane pre-strain levels) and activated with voltages between 2000 and 3500V. The experimental data are useful for determining constitutive model parameters as well as for validating models and simulation procedures for electromechanical coupling in EAP actuators. A novel approach is proposed for finite element analysis of dielectric elastomer actuator, which has been used in the present work for the evaluation of the experimental observations from circular actuators. Material parameters of different visco-hyperelastic models have been determined from a subset of the experimental data and the predictive capabilities of the models evaluated through comparisons with the remaining data. The prediction of the circular actuator behavior was satisfactory so that the proposed models might be useful for actuator design and optimization purposes. Limitations of the proposed constitutive model formulation are presented. [Copyright &y& Elsevier]

Abstract: This paper describes experiments with the surface resistance of IPMC actuators and sensors. We measure the surface resistance of samples working as sensors or as a voltage driven actuators, as well as when insulated. The results show that in all cases the surface resistance of a sample is highly correlated to material curvature. Based on these observations we present an equivalent circuit, with variable resistors representing surface resistance, that models IPMC materials. Our simulations with SPICE show that the equivalent circuit closely models the actual behaviour of IPMC sensors and actuators. We show that since the IPMC model works as a delay line with changing resistors, the curvature of the IPMC sample at a given point depends on the surface resistance. This, in turn, affects further bending of the sample. The modified equivalent circuit also explains the hysteresis of IPMC actuators as the signals along the surface are delayed. [Copyright &y& Elsevier]

Abstract: Piezoceramic actuators are often used when there is a need for high precision translation and are therefore of particular interest in the development of miniature robotic systems. In this paper the effect of miniaturisation on two dynamic and two quasi-static motion mechanisms has been experimentally evaluated using a miniature piezoceramic drive unit. The actuator design, comprising six piezoceramic multilayer bimorphs, and the rapid prototype process used to fabricate the monolithic multilayer structure, are described. Experiments show that for a mass of 1–10g, corresponding to the miniature robot considered, it is possible to use both dynamic and quasi-static motion mechanisms. With the present drive unit at low loads, the dynamic motion mechanisms are less demanding and work closer to the ideal case than quasi-static motion mechanisms. At higher loads the opposite will in general be true. Artefacts due to vibrations and bouncing in the vertical direction are the main reason for non-ideal behaviour when a small movable mass is used. In particular, movements generated by mechanisms utilizing a vertical velocity component are sensitive to a low mass. The design parameters to avoid or reduce these artefacts are identified and discussed. [Copyright &y& Elsevier]

Abstract: This paper describes a technique for replacing the conventional bonded bulk PZT transducer, commonly used in MEMS devices, with a screen printed equivalent. Previously, the piezoelectric activity available from screen printed PZT has been considerably lower than the bulk material, but recent developments in material composition and device structure have allowed screen printed structures to deliver powers equivalent to bulk devices. An actuator using the multilayer screen printed technique was designed for use in an ultrasonic flow-through separator, and its successful use is reported. [Copyright &y& Elsevier]

Abstract: Many applications involve actuated devices made of shape memory alloys, but the lack of efficient numerical tools hinders the development of such technologies. Software using a finite element method like ANSYS allows the user to predict complex responses of a system without extensive programming. In this paper, a homemade phenomenological 1D bilinear model is programmed through the USERMAT procedure in ANSYS. The model allows the representation of both mechanical and thermal hystereses. The martensitic transformation is controlled by transformation criteria similar to those used in conventional plasticity, and subcycles are modeled by a simple elastic return through the hysteresis. The model is validated through isothermal tensile testing, assisted two-way shape memory testing and stress generation testing, and a good agreement with experimental results is shown. Finally, thermomechanical response of a single-degree-of-freedom actuator is simulated as a typical application and a case study involving the shape change of a radio controlled aircraft wing shows the potential of the numerical simulations. [Copyright &y& Elsevier]

Abstract: A novel type of laser scanner employing a permanent magnetic suspension and spherical hinges has been developed. It consists of a single mirror based on linear electromagnetic actuators. This system has design features of playing the role of a two-dimensional tilt actuator by means of driving the electromagnetic actuators, and it provides good mechanical characteristics such as low distortion and damping, high optical angular deflection, and high dynamical performance (more than 1kHz). This paper describes the configuration of the device and presents experimental results to demonstrate its performance and effectiveness. [Copyright &y& Elsevier]

Abstract: One of the significant advantages of shape memory alloy (SMA) is its large recovery force generated by phase transition at specific temperature when initial deformation had been applied. Because of manufacturing and processing difficulties, SMA materials have been often used by the way of wires embedded in a variety of matrices when they are applied as actuators. Its great advantage, i.e. large generated force and displacement, raises, on the other hand, a problem at the SMA/matrix interface. The purpose of this paper is a proposition of a safety SMA actuator form with which no debonding occurs even when the maximum shear stress is generated by recovery force in SMA wires. Superior interfacial strength was obtained by the way of embedding SMA wires, memorized to sinusoidal curve shape, in the supported parts of the actuator. It provides holding stress over the fracture stress of SMA wires. An actuator form with eight SMA wires semi-embedded in two supporting parts made by CFRP was, thus, proposed. Besides, there exist again some difficulties to use SMA materials as active actuators, for example, its slow response speed. Particular driving system with cooling system is constructed in consideration with characteristics of SMA materials. The first and the second mode vibration suppressions of 2m beam were carried out to evaluate the efficiency of the proposed actuator, mounted on one side closed to the clamping edge, as an active actuator, and the system. Control effect on beam structure is, then, demonstrated experimentally even for around 5Hz. [Copyright &y& Elsevier]

Abstract: In this paper we study the potential use of a photovoltaic source as direct drive of electrostatic actuators, mainly for two reasons: first, because the I–V characteristic of a PV array has the shape of a current source limited in voltage and, second, because direct drive with galvanic isolation can be implemented at high voltages without using any dc/dc converter. We have used a standard PSpice model for a PV series array and a PSpice model of an electrostatic actuator. For sake of generality, the model for the PV array is the same one would like to use for the output circuit of a number of opto-couplers connected in series. Main parameters are: irradiance, I–V curve, and voltage, current and movement of the actuator (deflection) as a function of time. The number and surface of individual solar cells can be tailored to drive specific MEMS switches of high pull-in voltage value. As an example, a 14 cells-PV array, with a short circuit density current I sc =1.2nA, and open circuit voltage V oc =8.7V, would drive an electrostatic actuator having a pull-in voltage of 8.3V, with three orders of magnitude lower kinetic energy than the equivalent voltage-drive. Both, this reduction in the kinetic energy at the impact, as well as the low hold-on voltage in the photovoltaic actuation reduce the electric field across the dielectric, which may lead to better reliability performance. [Copyright &y& Elsevier]

Abstract: Dielectric elastomers are used for the realization of actuators with large deformations and belong to the group of so-called electroactive polymers (EAP). Models are required for the design and optimization of EAP actuators. Thereby the constitutive behavior of the elastomer is of crucial importance and typically uniaxial experiments are performed in order to determine the mechanical properties of these materials. In this paper a pre-strained circular actuator made of a dielectric elastomer is investigated: constitutive models based on uniaxial data are verified by comparing calculation results with experimental observations. An analytical model is derived for the instantaneous response to an activation voltage in the pre-strained circular actuator and a finite element model is used to simulate the time-dependent behavior. Hyperelastic models are used and three strain energy formulations (Yeoh, Ogden and Mooney-Rivlin) are compared in their predictive capabilities. The results of the calculations with the three strain energy forms differ significantly, although all forms were successfully fitted to the same uniaxial data set. Predictions of the actuator behavior with the Yeoh form agree to a great extent with the measurements. The results of the present work show that the circular actuator set-up represents a valid model system for the characterization and optimization of the electromechanical behavior of dielectric elastomers. [Copyright &y& Elsevier]

Abstract: A novel linear stepper piezoelectric actuator is reported in this paper. We designed the configuration of the actuator and fabricated its prototype. A testing system was set up to examine its dynamic characteristic. It has been found that the actuator moves in stepping mode under lower pulse frequency and achieves the highest velocity and the longest range when the duration of high level is 1ms. The new actuator has a displacement resolution of 0.1μm and a maximum velocity of 0.6mm/s. Its load may be 200g and its range may be several centimeters. Besides, it also has a simple configuration and is easy to be controlled. A high precision positioning system can be achieved with it. [Copyright &y& Elsevier]

This paper discusses research carried-out by ALSTOM POWER on the development and validation (on laboratory scale plant) of an observer-based fault detection identification and accommodation (FDIA) system for an electromechanical actuator. Three separate linear observers (or Kalman filters) are used to detect and identify faults corresponding to the system''s three sensors. Having successfully detected a sensor fault, a reconstructed measure of that output signal (generated from an observer not associated with that sensor) is used to replace the measured signal for feedback control. This ensures that the system can continue to function effectively even after a sensor failure. The experimental results demonstrate that this approach could significantly enhance the post-fault availability of such systems. [Copyright &y& Elsevier]