Mass Transfer Induced Hydraulic Actuation in Ionic Polymer-Metal Composites

Abstract

Discussed is the phenomenon of mass transfer-induced hydraulic actuation in ionic polymer-metal composites (IPMCs) strips with chemically plated surface electrodes. A new category of actuators as “mass transfer induced hydraulic actuators (MTIHAs)” is thus defined. Such mass transport of ions and water is across the thickness of the strip and ends up near the permeable metal electrodes. The imposition of an electric field causes the mobile hydrated cations that are conjugated to the polymeric network anions to undergo electrophoretic dynamic migration that can result in local deformation of the material. Such an electrophoretic behavior of the hydrated cations in IPMC causes the water to flow across the strip and partially leak out of the cathode side of the permeable electroded boundary. These leakages are undesirable because they lower the actuation performance. The IPMC is a good example of such MTIHAs. The advantage of MTIHAs is their potential to generate substantially high force densities if the leakage can be minimized or eliminated. Based upon this MTIHA concept, a certain manufacturing technique was developed to minimize the leakage and increase the force density of the conventional IPMCs by almost a factor of two (100% improvement in force). This phenomenon and the associated experimental results are presented in this paper.

Keywords

Ionic Polymer-Metal Composites

Get full access to this article

View all access options for this article.

References

1. Oguro, K. , Asaka, K. and Takenaka, H. (1993). “Actuator Element,” U.S. Patent #5,268,082.

2. Asada, A. , Oguro, K. , Nishimura, Y. , Misuhata, M. and Takenaka, H. (1995). “Bending of Polyelectrolyte Membrane-Platinum Composites by Electric Stimuli, I. Response Characteristics to Various Wave Forms,” Polymer Journal, 27:436-440.

3. Shahinpoor, M. , Adolf, D. , Segalman, D. and Witkowski, W. (1993). “Electrically Controlled Polymeric Gel Actuators,” U.S. Patent #5,250,167.

4. Shahinpoor, M. and Mojarrad, M. (2000). “Soft Actuators and Artificial Muscles,” U.S. Patent, #6,109,852.

5. Shahinpoor, M. , Bar-Cohen, Y. , Simpon, J.O. and Smith, J. (1998). “Ionic Polymer-Metal Composites (IPMC) as Biomimetic Sensors and Structures - A Review,” Smart Materials and Structures, 7:15-30.

6. Shahinpoor, M. and Kim, K.J. (2000). “The Effect of Surface-Electrode Resistance on the Performance of Ionic Polymer-Metal Composites (IPMC) Artificial Muscles,Smart Materials and Structures, 9:543-551.

7. de Gennes, P.G. , Okumura, K. , Shahinpoor, M. and Kim, K.J. (2000). “Mechanoelectric Effects in Ionic Gels,” Europhysics Letters, 50(4):513-518.

8. Shahinpoor, M. and Kim, K.J. (2001). “Ionic Polymer-Metal Composites: I. Fundamentals,” Smart Materials and Structures, 10:819-833.

9. Tokuyama Corp. , Technical Data (2000).

10.

10. Takenaka, H. , Torikai, E. , Kwami, Y. and Wakabayshi, N. (1982). “Solid Polymer Electrolyte Water Electrolysis,” International Journal of Hydrogen Energy, 7:397-403.

11.

11. Millet, P. , Pineri, M. and Durand, R. (1989). “New Solid Polymer Electrolyte Composites for Water Electrolysis,” Journal of Applied Electrochemistry, 19:162-166.

12.

12. Kim, K.J. , Shahinpoor, M. and Razani, A. (March 2000). “Preparation of IPMCs for Use in Fuel Cells, Electrolysis, and Hydrogen Sensors.” In: Proceedings of SPIE 7th International Symposium on Smart Structures and Materials, 3687:110-120.

13.

13. Davis, T. , Genders, D. and Pletcher, D. (1997). A First Course in Ion Permeable Membranes, The Electrochemical Consultancy, Hants, England.

14.

14. Escoubes, M. and Pineri, M. (1982). In: Eisenberg, A. and Yeager, H.L. (eds), Perfluorinated Ionomer Membranes, ACS Symposium Series, Vol. 180, Chapter 2.

15.

15. Yoshida, H. and Miura, Y. (1992). J. Membrane Science, 68:1-9.

16.

16. Wang, Q. , Du, X. , Xu, B. and Cross, L.E. (1999). “Electro-mechanical Coupling and Output Efficiency of Piezoelectric Bending Actuators,” IEEE Transactions on Ultrasonic, Ferroelectrics, and Frequency Control, 46(3):638-646.

17.

17. Pei, Q. , Inganas, O. and Lundstrom, I. (1993). “Bending Bilayer Strips Built from Polyaniline for Artificial Electrochemical Muscles,” Smart Materials and Structures, 2(1):1-5.

18.

also Chapter 6, “Ionic Polymer-Metal Composites”.

19.

19. Kim, K.J. and Shahinpoor, M. (2003). “Effective Diffusivity of Nanoscale Ion-Water Clusters within Ion-Exchange Membranes Determined by a Novel Mechano-Electric Technique,International Journal of Hydrogen Energy, 28(1):85-90.

20.

20. Shahinpoor, M. and Kim, K.J. (2002). “Solid-State Soft Actuator Exhibiting Large Electromechanical Effect,” Applied Physics Letter (APL), 80(18):3445-3447.

21.

21. Shahinpoor, M. and Kim, K.J. (2002). “A Novel Physically-Loaded and Interlocked Electrode Developed for Ionic Polymer-Metal Composites (IPMCs),” Actuator and Sensors: A. Physical, 96:125-132.

22.

22. Kim, K.J. and Shahinpoor, M. (2002). “Development of Three Dimensional Ionic Polymer-Metal Composites as Artificial Muscles,” Polymer, 43(3):797-802.

23.

23. Bernardi, N.T. and Beri, D. (1999). “Modeling and Study of the Quisi-Static Behavior of Piezoceramic Telescopy Actuation Architectures.” In: Proceedings of the Adaptive Structures and Materials Symposium, ASME AD-59, pp. 189-197.