1. Institute of Biomechanics and Medical Engineering, AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, P.R. China.
2. Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02139, USA.
3. Department of Mechanical Engineering, University of Sheffield, Sheffield, UK.
4. School of Mathematical and Statistical Sciences, University of Galway, Galway, Ireland.
5. Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province and Department of Engineering Mechanics, Zhejiang University, Hangzhou 310027, Zhejiang Province, P.R. China.