1. Center for Biomedical Engineering, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts 02115 and Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
2. Department of Mechanical Engineering, College of Engineering, Kyung Hee University, 1 Seochon, Giheung, Yongin, Gyeonggi 446-701, Republic of Korea
3. Department of Mechanical Engineering, Auburn University, 275 Wilmore Lab, Auburn, Alabama 36849, United States
4. Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02139, United States