1. Orthobiotiki Medical Center, 3-5 Sorou, Marousi, Athens 15125, Greece e-mail:
2. Foundation for Research & Technology—Hellas (FORTH), Institute of Electronic Structure and Laser (IESL), N. Plastira 100, Vasilika Vouton, Heraklion GR-700 13, Crete, Greece e-mail:
3. Department of Mechanical Engineering, University of California Berkeley, Berkeley, CA 94720 e-mail:
4. Fellow ASME Department of Mechanical Engineering, University of California Berkeley, Berkeley, CA 94720 e-mail: