1. School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, Liaoning Province, P. R. China
2. School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, Liaoning Province, P. R. China
3. Department of Bioengineering, University of Louisville, Louisville, KY 40292, USA
4. Department of Biomedical Engineering, School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
5. School of Rehabilitation Medicine, Shandong Second Medical University, Weifang 261053, Shandong Province, P. R. China
6. School of Biomedical Engineering, Faculty of Medicine, Dalian University of Technology, Dalian 116024, Liaoning Province, P. R. China