1. Department of Materials Science and Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
2. Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
3. Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
4. Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes (NHRI), Miaoli County 35053, Taiwan