Actuators electromechanical characterization

Carpi F, Chiarelli P, Mazzoldi A, De Rossi D (2003) Electromechanical characterization of dielectric elastomer planar actuators comparative evaluation of different electrode materials and different counterloads. Sens Actuators A 107 85... 

On the contrary, dielectric elastomer actuators are characterized by the necessity of high driving voltages, while offering interesting electromechanical performances, consisting of large, fast and stable deformations at moderate stresses. 

In order to characterize an IPMC actuator, it is necessary to electromechanically characterize it on the basis of actuation and force measurements. These methods are described in Chap. 10, IPMCs as EAPs How to Start Experimenting with Them of this book. Here, the teehniques used to characterize an IP and its plated electrodes are described (Rajagopalan et al. 2010 Wang et al. 2010 Panwar et al. 2012 Wang et al. 2014). These are also important for developing new actuator materials. 

The experimental setup for measuring eleetromechanical performance of an IPMC actuator consists of a clamp to mount the IPMC sample, a data recording device (e.g., digital oscilloscope or computer equipped for data acquisition), a function generator, a current amplifier, a force sensor, and a laser displacement sensor or a video camera (Figs. 4 and 5). The process diagram of electromechanical characterization is given in Fig. 6. 

Actuators Electrochemical impedance spectroscopy (EIS) Electrochemically driven actuators Voltage v. current control Electromechanical characterization Electrothermally driven actuators Ionic liquids (IL) Pulse-width-modulated (PWM) control signal... 

The forth direction, analytical modeling for understanding the behaviors of these materials, has been popular approach. Testing and characterization have been conducted for developing the models. Such attempts have been done especially for ionic polymer metal composites (IPMCs)[58, 70, 72, 120]. Nemab Nasser and his co-workers carried out extensive experimental studies on both Nafion- and Flemion-based IPMCs consisting of a thin perfluorinated ionomer in various cation forms, seeking to imderstand the fundamental properties of these composites, to explore the mechanism of their actuation, and finally, to optimize their performance for various potential applications[121]. They also performed a systematic experimental evaluation of the mechanical response of both metal-plated and bare Nafion and Flemion in various cation forms and various water saturation levels. They attempted to identify potential micromechanisms responsible for the observed electromechanical behavior of these materials, model them, and compare the model results with experimental data[122]. A computational micromechanics model has been developed to model the initial fast electromechanical response in these ionomeric materials[123]. A number... 

Newbury K-M, Leo D-J (2003) Linear electromechanical model of ionic polymer transducers - part I model development J Intell Mater Syst Struct 14 333-342 Nguyen XT, Goo NS, Nguyen VK, Yoo Y, Park S (2008) Design, fabrication, and experimental characterization of a flap valve IPMC micropump with a flexibly supported diaphragm. Sens Actuators A 141 640-648... 

The development of novel electromechanically active materials also demands suitable methods for characterization of their actuation performance. Actuators can be constructed in a variety of configurations - bending, linear length change (Torop et al. 2009 Ghaffari et al. 2013), and torsional actuation (Foroughi et al. 2011) being... 

Characterization of actuators involves measiuement of (a) electrical, (b) mechanical, and (c) electromechanical properties. Electromechanical measiue-ments can be divided into isometric, isotonic, and unobstructed actuation configuration. Additionally, (d) mechanoelectrical measurements are often performed to characterize the sensorial properties of the actuators. For reasons of space, mechanoelectrical characterization is not covered in this chapter. 

A couple of additional aspects must be considered in characterization of electromechanical response. The electrochemically driven actuators can also heatup during the working cycle. In contrast to the eleetrothermally driven actuators, this effect is usually not desired in case of the electrochemically driven actuators, as die actuator s constituents can significantly change their mechanical and electrical properties. In an extreme case, the temperature of the separator polymer can increase over its melting point, causing the actuator to short-circuit in turn. 

As explained in Sect. 3.5, also humidity absorption can change the electromechanical properties of an actuator considerably. Therefore, measurement of both -ambient temperature and relative humidity level - is necessary for proper eleetro-mechanical characterization of the actuators. 

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