1. Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis 08-03, Singapore 138634, Singapore
2. Peng Cheng Laboratory, Shenzhen 518055, P. R. China
3. Singapore Institute of Food and Biotechnology Innovation, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis 08-03, Singapore 138634, Singapore
4. Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore