1. Department of Energy Engineering; Konkuk University; Seoul 05029 Republic of Korea
2. Global Health Technology Research Center; College of Health Science; Korea University; Seoul 02841 Republic of Korea
3. Department of Biomedical Engineering; College of Health Science; Korea University; Seoul 02841 Republic of Korea
4. Department of Stem Cell Biology; School of Medicine; Konkuk University; Seoul 05029 Republic of Korea
5. Korea Research Institute of Standards and Science (KRISS); Daejeon 34113 Republic of Korea
6. Division of Electron Microscopy Research; Korea Basic Science Institute (KBSI); Daejeon 34133 Republic of Korea
7. Department of Mechanical Science and Engineering; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA