1. A.G. MacDiarmid NanoTech Institute, University of Texas at Dallas, Richardson, Texas 75083, United States
2. High-Performance Materials Institute, Florida State University, Tallahassee, Florida 32310, United States
3. Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
4. Center for Bio-Artificial Muscle and Department of Biomedical Engineering, Hanyang University, Seoul 133-791, South Korea