1. Department of Materials Science and Engineering, National University of Singapore 117574, Singapore, Singapore
2. College of Materials Science and Engineering, Nanjing Forestry University of China, Nanjing 210037, China
3. Department of Biomedical Engineering, National University of Singapore, Singapore 117583, Singapore
4. NUS Chongqing Research Institute, Liangjiang New Area, Chongqing 119077, China
5. State Key Laboratory of Efficient Production of Forest Resources, Beijing Forestry University of China, Beijing 100091, China
6. Department of Electrical Engineering, Hong Kong Chinese University, Hong Kong, China