1. Department of Neurosurgery, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan
2. Biomaterials Laboratory, Department of Mechanical Engineering, Chang Gung University, 259, Wen-Hwa 1st Roa, Kwei-Shan, Tao-Yuan 333, Taiwan
3. Graduate Institute of Medical Mechatronics, Chang Gung University, Tao-Yuan, Taiwan
4. Biomaterials Laboratory, Department of Mechanical Engineering, Chang Gung University, 259, Wen-Hwa 1st Roa, Kwei-Shan, Tao-Yuan 333, Taiwan.