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Journal of Sensors
Volume 2015, Article ID 353095, 6 pages
Research Article

Measuring Conductance of Phenylenediamine as a Molecular Sensor

1Department of Physics, Hankuk University of Foreign Studies, Yongin 449-791, Republic of Korea
2Department of Chemistry, Soonchunhyang University, Asan 336-745, Republic of Korea

Received 24 March 2015; Revised 4 May 2015; Accepted 4 May 2015

Academic Editor: Xiao-Miao Feng

Copyright © 2015 Taekyeong Kim and Tae Hyun Kim. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We report experimental measurements of molecular conductance as a single molecular sensor by using scanning tunneling microscope-based break-junction (STM-BJ) technique. The gap was created after Au atomic point contact was ruptured, and the target molecule was inserted and bonded to the top and bottom electrodes. We successfully measured the conductance for a series of amine-terminated oligophenyl molecules by forming the molecular junctions with Au electrodes. The measured conductance decays exponentially with molecular backbone length, enabling us to detect the type of molecules as a molecular sensor. Furthermore, we demonstrated reversible binary switching in a molecular junction by mechanical control of the gap between the electrodes. Since our method allows us to measure the conductance of a single molecule in ambient conditions, it should open up various practical molecular sensing applications.