1. Materials Science and Engineering, Iowa State University, Ames, IA 50010, USA.
2. Mechanical Engineering, Soft Materials and Structures Lab, Virginia Tech, Blacksburg, VA 24061, USA.
3. Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA 24061, USA.
4. Department of Mechanical and Materials Engineering, Smart Materials and Robotics Laboratory, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
5. Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.