1. Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583
2. Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608
3. National Key Laboratory of Special Environment Composite Technology, Harbin Institute of Technology, Harbin, 150001, China
4. NUS Suzhou Research Institute (NUSRI), Suzhou 215123, China