1. Department of Applied Physics; The Hong Kong Polytechnic University; Hong Kong China
2. Institute of Textiles and Clothing; The Hong Kong Polytechnic University; Hong Kong China
3. Department of Health Technology and Informatics; The Hong Kong Polytechnic University; Hong Kong China
4. Institute for Bioengineering; School of Engineering; The University of Edinburgh; King's Buildings, Mayfield Road Edinburgh EH9 3JL UK