1. NSF Research Triangle Materials Research Science and Engineering Center Department of Mechanical Engineering Duke University Durham NC 27708 USA
2. NSF Research Triangle Materials Research Science and Engineering Center Department of Biomedical Engineering Duke University Durham NC 27708 USA
3. Department of Mechanical Engineering Duke University Durham NC 27708 USA
4. Soft Active Materials Laboratory Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA
5. NSF Research Triangle Materials Research Science and Engineering Center Department of Chemistry University of North Carolina at Chapel Hill Chapel Hill NC 27599 USA
6. Department of Chemical and Biological Engineering The University of New Mexico Albuquerque NM 87131 USA
7. Department of Civil Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA