1. Singapore Institute of Manufacturing Technology (SIMTech), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-04, Singapore 138634, Singapore
2. Department of Biomedical Engineering, College of Design and Engineering, National University of Singapore, Singapore 117583, Singapore
3. London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK