1. School of Mechatronics Engineering Harbin Institute of Technology Harbin 150001 China
2. Department of Electrical and Computer Engineering National University of Singapore 4 Engineering Drive 3 Singapore 117583 Singapore
3. Center for Intelligent Sensors and MEMS (CISM) National University of Singapore 4 Engineering Drive 3 Singapore 117583 Singapore
4. NUS Graduate School for Integrative Science and Engineering National University of Singapore Singapore 117456 Singapore