1. School of Electrical and Computer Engineering
and Birck Nanotechnology Center, Purdue University, 1205 West
State Street, West Lafayette, Indiana 47907, United States
2. Weldon School of Biomedical Engineering, Purdue University, 206
S. Martin Jischke Drive, West Lafayette, Indiana 47907, United States
3. Department of Applied Physics, Yale University, New Haven, Connecticut 06250, United States