[1
]Harvard John A. Paulson School of Engineering and Applied SciencesHarvard University
Cambridge MA 02138 USA
[2
]State Key Laboratory for Strength and Vibration of Mechanical Structures and School
of AerospaceXi'an Jiaotong University Xi'an 710049 P. R. China
[3
]Department of MaterialsETH Zürich 8093 Zürich Switzerland
[4
]Kavli InstituteHarvard University Cambridge MA 02138 USA
[5
]Wyss Institute for Biologically Inspired EngineeringHarvard University Cambridge MA
02138 USA