* Corresponding authors

^a School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore
E-mail: ktyong@ntu.edu.sg

^b Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore

^c Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, P. R. China
E-mail: roy.law@polyu.edu.hk

^d CINTRA CNRS/NTU/THALES, UMI 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Singapore

^e School of Science, Changchun University of Science and Technology, International Joint Research Center for Nanophotonics and Biophotonics, Changchun 130000, P. R. China
E-mail: liulw@cust.edu.cn

^f Department of Electrical and Electronic Engineering, Auckland University of Technology, New Zealand
E-mail: peter.chong@aut.ac.nz