Electrically active polymers actuators

There is another type of electrically active polymer that is known as the electroconductive polymer, in which polymer chains contain long conjugated double bonds, and this chemical structure adds electroconductive properties to the polymers. In these cases, the electrically induced deformation is considered to have originated from the electrochemical reactions such as the oxidation and reduction of the polymer chain. For the deformation, some additives such as dopants have been known to be necessary for effective actuation. Therefore, the electrical actuation of these materials has been... 

DE De Rossi, P Chiarelli, G Buzzigoli, C Domenici, L Lazzeri. Contractile behavior of electrically activated mechanochemical polymer actuators. Trans Am Soc Artif Intern Organ 32 157-162, 1986. 

Today the number of electroactive polymers has grown substantially. There currently exists a wide variety of such materials, ranging from rigid carbon-nanotubes to soft dielectric elastomers. A number of reviews and overviews have been prepared on these and other materials for use as artificial muscles and other applications [1, 2, 7, 10, 11, 13-28]. The next section will provide a survey of the most common electrically activated EAP technologies and provide some pertinent performance values. The remainder of the paper will focus specifically on dielectric elastomers. Several actuation properties for these materials are summarized in Table 1.1 along with other actuation technologies including mammalian muscle. It is important to note that data was recorded for different materials under different conditions so the information provided in the table should only be used as a qualitative comparison tool. 

Besides the intrinsic conductive polymers, some deformable polymers, such as shape-memory polymers, are usually activated by heating. After incorporating with conductive fillers, such as carbon nanomaterials, they can be simulated by the electricity through Joule heating (Liu et al., 2009 Hu and Chen, 2010 Koerner et al., 2004). This kind of electro thermally active polymer composites can produce expansion/contraction and bending behaviors upon with the electricity. Moreover, these actuators can work durably... 

De Rossi, D. Chiarelh, P. Buzzigoli, G. Domenici, C. Lazzeri, L. Contractile behaviour of electrically activated mechanochemical polymer actuators. Trans. Am. Soc. Artif. Internal Organs, 32 (1986), pp. 157-162... 

This chapter was adapted from in part, by permission, M. Otake, M. Inaba, and H. Inoue. Development of Electric Environment to control Mollusk-Shaped Gel Robots made of Electro-Active Polymer PAMPS Gel , Proceedings of SPIE vol.3987 Electroactive Polymer Actuators and Devices (EAPAD) Y. Bar-Cohen (ed.), pp.321-330, 2000 M. Otake, Y. Kagami, M. Inaba, and H. Inoue, Dynamics of Gel Robots made of Electro-Active Polymer Gel , Proceedings of IEEE International Conference on Robotics and Automation, pp.1458-1462, 2001 M. Otake, Y. Kagami, M. Inaba, and H. Inoue, Motion design of a starfish-shaped gel robot made of electro-active polymer gel . Robotics and Autonomous Systems, vol. 40, pp. 185-191, 2002. 

Mojarrad have been experimenting with various chemically active as well as electrically active ionic polymers and their metal composites as artificial muscle actuators. 

The ability to change film dimensions by altering the water content in the films has driven Okuzaki et al. to employ PEDOT PSS as an electro-active polymer actuator. Film contractions of 2.4% to 4.5 % depending on relative humidity were realized by applying an electrical bias and removing water from the films due to Joule heating. 

Nanocomposites offer opportunities to enhance the performance of active polymers. Opportunities arise from the extensive polymer-nanoparticle interface the responsiveness of the percolative nanoparticle network and the impact of nanoparticles on the local electric field. For example, carbon nanotube addition to shape memory polyurethane increases blocking stress and provides electrical and optical triggering of recovery. Similarly, carbon nanotubes modify the local electric field in the surrounding polymer, decreasing the actuation voltage for ferroelectric polymers. Challenges facing characterization and the establishment of structure-property correlations will be discussed. 

In recent several years, super-capacitors are attracting more and more attention because of their high capacitance and potential applications in electronic devices. The performance of super-capacitors with MWCNTs deposited with conducting polymers as active materials is greatly enhanced compared to electric double-layer super-capacitors with CNTs due to the Faraday effect of the conducting polymer as shown in Fig. 9.18 (Valter et al., 2002). Besides those mentioned above, polymer/ CNT nanocomposites own many potential applications (Breuer and Sundararaj, 2004) in electrochemical actuation, wave absorption, electronic packaging, selfregulating heater, and PTC resistors, etc. The conductivity results for polymer/CNT composites are summarized in Table 9.1 (Biercuk et al., 2002). 

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