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In this work, the fabrication of Rochelle salt based piezoelectric structures is illustrated. Structures composed of paper and Rochelle salt are easily manufactured using simple processes. Both manufacturing and the material itself are environmental friendly. Additionally Rochelle salt is biocompatible. In the paradigm of a cleaner piezoelectric technology, the fabrication of active sensing or actuating devices is developed. Thus processing method, material and piezoelectric properties have been studied: (1) pure crystals are used as acoustic actuator, (2) properties of paper impregnated with Rochelle salt are detailed, (3) charge generation is demonstrated on the impregnated material. Actuating and sensing devices are reported in order to highlight the potential of this green piezoelectric material. [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]

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]

This paper reports on the development of a unique Digital Loudspeaker Array solution, based on Pb(Zr 0.52 ,Ti 0.48 )O 3 (PZT) thin-film actuated membranes, arranged in a matrix and which operate in a binary manner by emitting short pulses of sound pressure. Using the principle of additivity of pressures in the air, it is possible to reconstruct audible sounds. For the first time, electromechanical and acoustic characterizations were reported on 256 MEMS membranes DLA. Sounds audible as far as several meters from the loudspeaker have been generated using low-voltage. [ABSTRACT FROM AUTHOR]

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: 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: 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]