1. Chulabhorn International College of Medicine, Thammasat University, Pathum Thani 12120, Thailand
2. Thammasat University Research Unit in Synthesis and Applications of Graphene, Thammasat University, Pathum Thani 12120, Thailand
3. Department of Physics, Faculty of Science and Technology, Thammasat University, Pathum Thani 12120, Thailand