chapter 2, Natural Muscle as a Biological System

In Topic 2 Natural Muscles from: Electroactive Polymer (EAP) Actuators as Artificial Muscles: Reality, Potential, and Challenges, Second Edition, Second

Editor(s): Yoseph Bar-Cohen

Author(s): Gerald H. Pollack, Felix A. Blyakhman, Frederick B. Reitz, Olga V. Yakovenko, Dwayne L. Dunaway

Published: 18 March 2004

Chapter DOI: http://dx.doi.org/10.1117/3.547465.ch2

Chapter Page Count: 20 pages

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Front Matter

Topic 1 Introduction
1. EAP History, Current Status, and Infrastructure

Topic 2 Natural Muscles
2. Natural Muscle as a Biological System

3. Metrics of Natural Muscle Function

Topic 3 EAP Materials
4. Electric EAP

5. Electroactive Polymer Gels

6. Ionomeric Polymer-Metal Composites

7. Conductive Polymers

8. Carbon Nanotube Actuators: Synthesis, Properties, and Performance

9. Molecular Scale Electroactive Polymers

Topic 4 Modeling Electroactive Polymers
10. Computational Chemistry

11. Modeling and Analysis of Chemistry and Electromechanics

12. Electromechanical Models for Optimal Design and Effective Behavior of Electroactive Polymers

13. Modeling IPMC for Design of Actuation Mechanisms

Topic 5 Processing and Fabrication of EAPs
14. Processing and Fabrication Techniques

Topic 6 Testing and Characterization
15. Methods of Testing and Characterization

Topic 7 EAP Actuators, Devices, and Mechanisms
16. Application of Dielectric Elastomer EAP Actuators

17. Biologically Inspired Robots

18. Applications of EAP to the Entertainment Industry

19. Haptic Interfaces Using Electrorheological Fluids

20. Shape Control of Precision Gossamer Apertures

Topic 8 Lessons Learned, Applications, and Outlook
21. EAP Applications, Potential, and Challenges

Back Matter

Preview

Chapter Contents

2.1 Conceptual Background
2.2 Structural Considerations
2.3 Does Contraction Involve a Phase Transition?
2.4 Molecular Basis of the Phase Transition
2.5 Lessons from the Natural Muscle System That May Be Useful for the Design of Polymer Actuators
2.6 References

Excerpt

Muscle is the natural contractile system that artificial systems attempt to emulate. For proper emulation it is evidently necessary to understand the basic underlying mechanism. In the material that follows, we consider the evidence that muscle is a polymer gel, and that the gel's polymeric filaments contract by a polymer-gel phase-transition. This is an unorthodox conclusion, and we therefore begin by considering the relevant background.

2.1 Conceptual Background

Until the mid-1950s muscle contraction was held to occur by a protein-folding mechanism [for review, cf. A. F. Huxley, 1957]. The folding mechanism is similar enough to the one that will be suggested here that it may be considered a progenitor.

With the discovery of interdigitating thick and thin filaments in the mid-1950s, it was tempting to discard the notion of folding, and suppose instead that contraction arose out of pure filament sliding. This supposition led H. E. Huxley and Sir Andrew Huxley to examine independently whether the interdigitating filaments (Fig. 1) remained at constant length during contraction. Their optical microscopic studies of muscle-striation patterns were published back-to-back in Nature [Huxley and Hanson, 1954; Huxley and Niedergerke, 1954].

http://dx.doi.org/10.1117/3.547465.ch2

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