[1] Tufts Univ, Dept Mech Engn, Medford, MA 02155 USA
[2] Tufts Univ, Dept Biol, Medford, MA 02155 USA
[3] Ecole Polytech Fed Lausanne, Dept Mech Engn, Lausanne, Switzerland
[4] Cornell Univ, Mech & Aerosp Engn, Ithaca, NY USA
[5] MIT, Mech Engn, Cambridge, MA 02139 USA