Department of Biomedical Engineering, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, China

Received 2 December 2019 Accepted 14 January 2020

Correspondence to Wang Lin, PhD, Department of Biomedical Engineering, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China, Tel: +086 22 27892060; e-mail: [email protected].