1. Division
of Electrical Engineering and Computer Science, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
2. Japan Society for the Promotion of Science, Ichiban-cho, Chiyoda, Takyo 102-1192, Japan
3. Bio-AFM
Frontier Research Center, Kanazawa University, Kakuma-michi, Kanazawa 920-1192, Japan
4. ACT-C, Japan Science and Technology Agency, Honcho 4-1-9, Kawaguchi 3320-0012, Japan