1. School of Mechanical Engineering; Gwangju Institute of Science and Technology (GIST); 123 Cheomdangwagi-ro, Buk-gu Gwangju 61005 Republic of Korea
2. Research Institute for Solar and Sustainable Energies; Gwangju Institute of Science and Technology (GIST); 123 Cheomdangwagi-ro, Buk-gu Gwangju 61005 Republic of Korea
3. Department of Medical Engineering; California Institute of Technology; Pasadena CA 91125 USA
4. Department of Electrical Engineering; California Institute of Technology; Pasadena CA 91125 USA