1. Department of Mechanical Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
2. Applied Physics Course, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu City 501-1193, Japan.
3. School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
4. Center for Medical Engineering and Informatics, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.