1. School of Materials Science and Engineering; Nanyang Technological University; 50 Nanyang Avenue 639798 Singapore
2. Biomedical Microdevices Research Laboratory; Shenzhen Institutes of Advanced Technology; The Chinese Academy of Sciences; 1068 Xueyuan Avenue Shenzhen 518055 P. R. China
3. Singapore Institute of Manufacturing Technology; 71 Nanyang Drive 638075 Singapore