1. Mechanical and Aerospace Engineering Department, University of California, Los Angeles (UCLA), Los Angeles, California 90095, USA
2. Department of Computer Science, National Tsing Hua University, Hsinchu, Taiwan
3. Department of Chemistry, and Institute of Biological Interfaces, Sogang University, Seoul 04107, Korea
4. Computer Science Department, University of California, Los Angeles (UCLA), Los Angeles, California 90095, USA
5. Department of Bioengineering, University of California, Los Angeles (UCLA), Los Angeles, California 90095, USA
6. Department of Computer Science and Engineering, The Chinese University of Hong Kong, Hong Kong, China
7. California NanoSystems Institute, University of California, Los Angeles (UCLA), Los Angeles, California 90095, USA