1. Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
2. School of Natural Sciences, University of California Merced, Merced, California 95344, USA
3. Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189, China
4. Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520, USA
5. Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA