1. School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
2. Research Centre for Information Technology, Shenzhen Institute of Information Technology, Shenzhen 518172, P. R. China
3. Medico-Engineering Cooperation on Applied Medicine Research Center, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
4. Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215011, P. R. China
5. Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States