1. Singapore-MIT Alliance for Research and Technology (SMART), 1 CREATE Way, CREATE Tower, Singapore 138602, Singapore
2. Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge MA 02139, USA
3. Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge MA 02139, USA
4. GR Harrison Spectroscopy Laboratory, 77 Massachusetts Ave, Cambridge MA 02139, USA