1. Department of Applied Physics The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong SAR 999077 P. R. China
2. Faculty of Science Kunming University of Science and Technology Kunming Yunnan 650032 P. R. China
3. School of Fashion and Textiles The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong 999077 P. R. China
4. Research Institute of Intelligent Wearable Systems The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong SAR 999077 P. R. China