A single molecule sensing or detecting device includes a first electrode and a second electrode separated from the first electrode by a gap. The first electrode and the second electrode have an opening formed therethrough. At least one of the first electrode and the second electrode is functionalized with a recognition molecule. The recognition molecule has an effective length LI and is configured to selectively bind to a target molecule having an effective length L2. The size of the gap is configured to be greater than L2, but less than or equal to the sum of LI and L2.