Molecular detection based on the electrical conductance of gold nanoparticle arrays

We report a molecular sensing method based on changes in the electrical conductance of lithographically defined gold nanoparticle (NP) arrays immersed in an analyte solution. As the closely spaced NPs are enlarged due to the analyte-mediated deposition of gold ions onto their surfaces, the conductance increases steeply near the critical time (tc) at which conducting pathways begin to form in the NP arrays. tc decreases with increasing analyte concentration in the solution. The temperature dependence of the conductance of the modified NP arrays confirms the good electrical contacts established between the newly formed nanoclusters on the NP surfaces. Our results demonstrate that the electrical conductance through metal NP arrays can be employed as a sensitive and reliable analytical signal for NP-based sensors, which do not require any post-processing for the formation of electrical contacts between the NPs.