1. School of Electronic Information and Electrical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
2. Shanghai Engineering Research Centre for Intelligent Diagnosis and Treatment Instrument, Shanghai 200240, P. R. China
3. Key Lab. for Thin Film and Microfabrication Technology of Ministry of Education, Shanghai 200240, P. R. China
4. Centre for Advanced Electronic Materials and Devices (AEMD), Shanghai Jiao Tong University, Shanghai 200240, P. R. China
5. Department of General Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China