1. Biomedical Engineering and Biomechanics Center, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, P. R. China
2. HST-Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA 02129, USA
3. School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore