1. Department of Electrical and Computer Engineering; National University of Singapore; 4 Engineering Drive 3 Singapore 117583
2. Graduate School for Integrative Sciences and Engineering; National University of Singapore; Centre for Life Sciences (CeLS); #05-01, 28 Medical Drive Singapore 117456 Singapore
3. Institute of Materials Research and Engineering Agency for Science Technology and Research (A*STAR); Innovis; #08-03 2 Fusionopolis Way Singapore 138634
4. College of Physics and Electronic Engineering; Hengyang Normal University; Hengyang 421002 China
5. School of Physics & Astronomy; University of Birmingham; Birmingham B15 2TT UK