1. Department of BiophysicsInstitute of Quantum BiophysicsSungkyunkwan University Suwon 16419 Korea
2. National Research Council Canada M‐50 1200 Montreal Road Ottawa Ontario K1A 0R6 Canada
3. Department of Printed Electronics EngineeringSunchon National University Sunchon 57922 Korea
4. Materials and Structure LaboratoryTokyo Institute of Technology Yokohama 226–8503 Japan
5. Electrical Engineering and Computer SciencesUniversity of California Berkeley CA 94720 USA