Mass-Produced Nanogap Sensor Arrays for Ultrasensitive Detection of DNA

Abstract

In this report, an electrical detection scheme for the quantification of DNA using a nanogap sensor array is detailed. The prime objective is to develop a novel sensing procedure, based on the electronic transduction mechanism, which would mitigate the problems intrinsic to nanostructure-based biosensing devices. Design considerations of the sensor array take into account the feasibility of mass production in a cost-effective way by using standard silicon microfabrication technologies. The sensing mechanism relies on bridging the nanogap upon hybridization of the two termini of a target DNA with two different surface-bound capture probes, followed by a simple metallization step. About 2 orders of magnitude enhancement in conductance, as referred to a clean background (<1.0 pS) observed at a control sensor, was obtained in the presence of as little as 1.0 fM target DNA. This sensitivity is comparable to the best of electrochemical/electrical biosensors. A linear relationship between the conductance and the DNA concentration was obtained from 1.0 fM to 1.0 pM with an exceptional signal intensity of 2.1 x 10(4)% change per unit concentration. This change in conductivity is so large that it can unambiguously detect the concentration of DNA quantitatively and may obviate the need for target amplification used in current DNA tests. Moreover, the sensor array exhibited excellent single-base mismatch discrimination due to its unique vertically aligned nanostructure and the two-probe configuration.