Single molecule DNA device measured with triple-probe atomic force microscope

We have measured the electric properties of a three-terminal single molecule DNA device with a triple-probe atomic force microscope (T-AFM). The T-AFM permits us to connect a single DNA molecule with carbon nanotube (CNT) electrodes as source, drain, and gate terminals. As the gate bias voltage is increased, the voltage gap region decreased in the current–voltage (I–V) curves. Furthermore, we can observe the clear steps in the I–V curve at crossing the DNA molecule and the CNT-gate electrode with gate biased.