1. College of Materials Science and Engineering, Sichuan University, Chengdu 610064, China
2. Sichuan Province Key Laboratory of Information Materials, Southwest Minzu University, Chengdu, 610041, P. R. China
3. Department of Biomedical Engineering Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089, USA
4. Sichuan Province Key Laboratory of Information Materials and Devices Application, Chengdu University of Information Technology, Chengdu 610225, P. R. China