1 Department of Engineering Product Design, Singapore University of Technology and Design, Singapore, Singapore.
2 Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore, Singapore.
3 Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
4 Department of Engineering Product Design, Singapore University of Technology and Design, Singapore, Singapore. towchong@sutd.edu.sg.
5 Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore. chengwei.qiu@nus.edu.sg.
6 Department of Engineering Product Design, Singapore University of Technology and Design, Singapore, Singapore. r_zhao@tsinghua.edu.cn.
7 Center for Brain-Inspired Computing Research (CBICR), Department of Precision Instrument, Tsinghua University, Beijing, China. r_zhao@tsinghua.edu.cn.