1. NanoMEMS Research, LLC 1 , Irvine, California 92604, USA
2. Department of Electrical Engineering, University of South Carolina 2 , Columbia, South Carolina 29208, USA
3. Department of Electrical and Computer Engineering, Ohio State University 3 , Columbus, Ohio 43210, USA
4. Institute of Electronics and Nanotechnology, Georgia Institute of Technology 4 , Atlanta, Georgia 30332, USA