1. Institute of Physics, Academia Sinica, Taipei 115, Taiwan
2. Department of Paper Technology, Indian Institute of Technology, Roorkee, Saharanpur 247 001, India
3. Tzu Chi General Hospital, Taipei, Taiwan and Institute of Biomedical Engineering, National Taiwan University, Taipei 100, Taiwan
4. Institute of Biomedical Engineering, National Taiwan University, Taipei 100, Taiwan
5. Institute of Physics and Research Center for Applied Science, Academia Sinica, Taipei 115, Taiwan