Molecular Length Based Target Identification using a Nano-Gap Sensor

This paper reports the detection of gas molecules with an identical functional group, but in different lengths due to varying numbers of CH 2 backbone units, by utilizing a nano-gap gas sensor. Significance of such a gas sensor lies on its ability to distinguish molecular lengths by down to 0.15nm in this testing. The fabricated nano-gap sensor, after being functionalized by a specific linker on the surface, successfully captured all three target gas molecules of 2-CH 2 -diamine (0.3nm), 3-CH 2 -diamine (0.45nm) and 5-CH 2 -diamine (0.75nm). The capture of each target molecules demonstrated significant differences in both resistance and capacitances, resulting in successful identification of 2-CH 2 -diamine (0.3nm), 3-CH 2 -diamine (0.45nm) and 5-CH 2 -diamine (0.75nm) by producing different on/off resistance ratios of 105, 2905 and 3832 and capacitance changes of 4.45pF, 16.21pF and 26.64pF, indicating the capability of identifying multiple gas molecules in different lengths despite identical functional groups.