1. School of Physical and Mathematical Sciences Nanyang Technological University Singapore 637371 Singapore
2. Institute of Materials Research and Engineering Agency for Science, Technology and Research (A*STAR) 2 Fusionopolis Way, #08-03, Innovis Singapore 138634 Singapore
3. Singapore Institute of Manufacturing Technology (SIMTech) Agency for Science, Technology and Research (A*STAR) 2 Fusionopolis Way, #08-04, Innovis Singapore 138634 Singapore
4. School of Electrical and Electronic Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore