In this work, the monolayer of gold nanoparticles within 72 nm gap has been proposed to function as a DNA sensor. The authors suggest that the nanoparticles in the nanogap could act as hopping sites which amplify the conductance of hybridized DNA strands. The conductance amplification between single strand and hybridized DNAs through gold nanoparticles is observed. Various concentrations of capture and target DNA are discussed for optimal hybridization sensing purpose. With the help of 1 nM capture DNAs, this sensor is able to analyze target DNA sequences at very low concentration of 1 fM. Furthermore, by means of adjusting the denature temperature to 60 degrees C, even single mismatch hybridization could be discriminated.