1. Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument, School of Biomedical Engineering, Shenzhen Campus of Sun Yat-Sen University, Shenzhen 518107, P. R. China
2. State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-Sen University, Guangzhou 510006, P. R. China
3. Research Institute of Sun Yat-Sen University in Shenzhen, Shenzhen 518057, P. R. China