1. Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130, United
States
2. State Key Laboratory
of Bioelectronics,
School of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096, P.R. China
3. Condensed Matter Physics and Materials
Science Department, Brookhaven National Laboratory, Upton, New York 11973, United States
4. Hitachi High Technologies America, Inc., 944 Clopper Road, Gaithersburg, Maryland
20878, United States