1. Bio-imaging Team, Safety Measurement Institute, Korea Research Institute of Standard and Science (KRISS), Daejeon 34113, Republic of Korea
2. Department of Nano Science, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
3. Department of Brain Sciences, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea
4. IonTOF Technologies GmbH, Helsenbergstrasse 15, 48149 Münster, Germany