IPMCs composites

Figure 10-Frequency dependence of bending deformation of IPMC composite muscles...

Kim KJ, Shahinpoor M (2002) A novel method of manufacturing three-dimensional ionic polymer-metal composites (IPMCs) bomimetic sensors, actuators and artificial muscles. Polymer 43 797... 

Ionic Polymeric Metallic Composites (IPMCs) are a class of EAPs that exhibit characteristics of both actuators and sensors, Shahinpoor et al. [6—11]. The flexibility of an IPMC makes it possible to be applied both in small and large deflection applications. Successive photographs of an IPMC strip are shown in Fig. 2.1 that demonstrates very large deformation (up to 8 cm) in the presence of low voltage. The sample is 10 mm wide, 80 mm long, and 0.34 mm thick. The time interval is 1 s and the actuation voltage is 4 V DC. 

The purpose of this book is to provide a focused, in-depth, yet self-contained treatment of recent advances made in several most promising EAP materials. In particular, the book covers two classes of ionic EAPs, ionic polymer-metal composites (IPMCs) and conjugated polymers, and one class of electronic EAP materials, dielectric elastomers. Ionic EAPs realize actuation through ion transport, and thus require very low voltages (a few volts) to operate, but their bandwidths are typically lower than tens of Hz. On the other hand, dielectric elastomers rely on electrostatic forces to operate and thus require high actuation voltages (kilovolts), but... 

The fabrication of an IPMC is separated into two preparation processes the initial compositing process (ICP) and the surface electroding process (SEP). Shahinpoor and Kim have reported that the different microstructures occur in the two processes a roughened electrode surface forms during the ICP, and the well deposited Pt layer grows during SEP [Shahinpoor and Kim (2001b)]. To ensure the quality of IPMCs, both preparation processes must be conducted. 

Fig. 2.3 Top Cross-sectional scanning electron micrographs of the micromorphology of Pt ionic-polymer metal composites after treatment of the initial compositing process (ICP) (a) and the surface electroding process (SEP) (b). The bottom images show the cross-sectional view of the digital scanning microscope of the Pt IPMCs, where the treatment of ICP is again shown on the left and SEP on the right. Reprinted from [Park et al. (2008)] with permission from Cambridge University Press.

Fig. 8.4 illustrates the schematic of the composite beam. The IPMC is treated as a homogeneous beam for simplicity. We denote the IPMC, insulating layer, and PVDF as layers 1 through 3, respectively. The stiffness of the beam can be characterized by the spring constant... 

Experiments were conducted to measure the stiffness of an IPMC beam and two IPMC-PVDF composite beams with different insulating layer thickness (30 pm vs. 100 pm). The two composite beams were named IPMC/PVDFl and IPMC/PVDF2, respectively. As illustrated in Fig. 8.5(a), the cantilevered beam under measurement was pushed quasi-statically at the tip by a linear actuator. Between the linear actuator and the tip was a PVDF-based micro force sensor measuring the interaction force. The tip displacement was measured with a laser distance sensor. Fig. 8.5(b) shows the measured tip displacement together with the corresponding force for each beam, with the spring constants determined to... 

Fig. 8.11 compares the displacement trajectories of the IPMC-PVDF composite beam measured by a laser sensor and by the integrated PVDF... 

The micro-force sensor, attached at the end of the IPMC-PVDF beam, has a similar structure as the IPMC-PVDF composite beam shown in Fig. 8.16, except that the IPMC layer is replaced by a (relatively) rigid passive film. In the prototype, we used 200 pm thick polyester film as the middle layer. The same charge amplifier circuit as in Fig. 8.17, with possibly different gains, is used for the force sensor. Analogous to the case of measuring the bending displacement, one can derive the sensitivity of the force sensor in terms of the electromechanical properties and dimensions of the layers [Chen et al. (2008)]. 

Chen, Z., Tan, X. and Shahinpoor, M. (2005). Quasi-static positioning of ionic polymer-metal composite (IPMC) actuators, in Proceedings of the lEEE/ASME International Conference on Advanced Intelligent Mechatronics (Monterey, CA), pp. 60-65. 

Costa Branco, P. J. and Dente, J. A. (2006). Derivation of a continuum model and its electric equivalent-circuit representation for ionic polymer-metal composite (IPMC) electromechanics. Smart Materials and Structures 15, pp. 378-392. 

Punning, A., Kruusmaa, M. and Aabloo, A. (2007a). A self-sensing ion conducting polymer metal composite (IPMC) actuator. Sensors and Actuators A 136, pp. 656-664. 

Shahinpoor, M., Bar-Cohen, Y., Simpson, J. O. and Smith, J. (1998). Ionic polymer-metal composites (ipmcs) as biomimetic sensors, actuators and artificial muscles - a review. Smart Materials and Structures 7, 6, p. R15. 

Shahinpoor, M. and Kim, K. J. (2000). The effect of surface-electrode resistance on the performance of ionic polymer-metal composite (IPMC) artificial muscles, Smart Materials and Structures 9, pp. 543-551. 

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