Electromechanical actuators electrodes

IPMCs are smart materials that exhibit electromechanical (actuator) and mechanoelectrical (sensor) applications. Table 9.1 shows performance properties of state-of-the art IPMCs [5]. They bend quickly under a low voltage, as first reported by Oguro and his co-workers [6]. Later, Abe et al. introduced the important role of existent counter ions and their influence during the bending [7]. Asaka and Oguro introduced a theory of the actuation mechanisms [8] Shahinpoor and Kim demonstrated that the ionic polymer actuator performance depends on the type of cation [9] and further developed a two-step fabrication method [10] in accordance with their findings. In addition, other groups tried to incorporate various metals as electrode materials to articulate physical properties or electrical responses [11-14]. 

It is also essential to observe the morphologies of the plated electrodes using SEM, TEM, or AFM. Figure 4 shows a SEM image of a cross section of a Pt-plated Nation 117 membrane. As can be seen from the figure, the morphology of the plated electrodes determines the electrochemical and mechanical properties of the IPMC and thus its electromechanical actuation performance. 

The electromechanical actuation tests were ideally performed using a potentiostat to control the applied voltage or current and the type of signal (sinusoidal, triangle and square wave). As for trilayer devices operating in electrolyte medium, the working electrode input of the potentiostat is connected to one electrode of the actuator while... 

Kosidlo U, et al (2013) Nanocarbon based ionic actuators-a review. Smart Mater Struct 22 104022 Li J, et al (2011) Superfest-response and ultrahigh-power-density electromechanical actuators based on hierarchal carbon nanotube electrodes and chitosan. Nano Lett 11 4636-4641 Lima MD, et al (2012) Electrically, chemically, and photonically powered torsional and tensile actuation of hybrid carbon nanotube yam muscles. Science 338 928-932 Liu Q, et al (2014) Nanostructured carbon materials based electrothermal air pump actuators. Nanoscale 6 6932-6938... 

The introduction of carbonaceous electrode materials for the electrochemically driven actuators intersected two classes of electrochemical devices that were considered as being separate beforehand - the electromechanical actuators and the electric double-layer capacitors (also known as supercapacitors). Although the... 

Carpi, F., Chiarelli, P., Mazzoldi, A., and De Rossi, D., Electromechanical characterisation of dielectric elastomer planar actuators Comparative evaluation of different electrode materials and different counterloads, Sensors Actuators, A107, 85, 2003. 

Takeuchia I, Asakaa K, Kiyoharaa K et al (2009) Electromechanical behavior of a fully plastic actuator based on dispersed nano-caibon/ionic-liquid-gel electrodes. Carbon 47 1373-1380... 

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 Phys 107(l) 85-95. doi 10.1016/S0924.4247 (03)00257-7... 

Reversible electrochemical actuators comprise of an anode, a cathode and a separating electrolyte. Either electrode or both can be conducting polymers. However, other redox materials such as graphite have also been used as electromechanical electrodes. The nature of redox processes for conducting polymer electrodes has been found to be rate dependent. For instance, an electrode that is anion doped can be reduced either during the addition of cations or the removal of anions. 

FIGURE 8.81 Schematic representation of three states during the electromechanical cycle of a rocking-chair-type, bimorph actuator. Both electrodes have the same concentration of dopant (K ) when the cantilever is undistorted, and electrochemical transfer of dopant between electrodes causes bending either to the right or to the left. (From Baughman, R.H., Synth. Met, 78, 339, 1996. With permission.)... 

Liu S, Liu Y, Cebeci H, de Villoria R G, Lin J H, Wardle B L and Zhang Q M (2010) High electromechanical response of ionic polymer actuators with controUed-morphology ahgned carbon nanotube/nafion nanocomposite electrodes, Adv Fmct Mater 20 3266-3271. 

Dielectric elastomer transducers are based on the electromechanical response of an elastomeric dielectric film with comphant electrodes on each surface. These transducers may be actuators, generators, or sensors. In aU cases, the basic stmcture is the same. 

To increase the electromechanical coupling and allow for anisotropic and thus directional actuation and sensing, the concept of interdigitated electrodes has been introduced by Hagood et al. [90] for monolithic piezoelectric laminae, as shown in Figure 5.2(b). Thereby in-plane placement of the parallel directions of polarization and electric field strength is permitted. These directions... 

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