1. NUS Suzhou Research Institute (NUSRI), Suzhou, Industrial Park, Suzhou 215123, People's Republic of China
2. Center for Intelligent Sensors and MEMS, Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576
3. Division of Physics and Applied Physics, Centre for Disruptive Photonic Technologies, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
4. Institute of Microelectronics (IME), 11 Science Park Road, Singapore 117685