1. Paulson School of Engineering and Applied Sciences and Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA
2. College of Health and Rehabilitation Sciences, Sargent College, Boston University, Boston, MA
3. Department of Physical Medicine and Rehabilitation, Harvard Medical School, Cambridge, MA
4. College of Health and Rehabilitation Sciences, Sargent College, Boston University, Boston, MA; Paulson School of Engineering and Applied Sciences and Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA; Department of Physical Medicine and Rehabilitation, Harvard Medical School, Cambridge, MA