A double gate DNA FET based on solution processed ZnO nano layers for high sensitivity and low cost oligonucleotide hybridization detection

Abstract

In this paper, an oligonucleotide hybridization detection sensor is presented. The sensor uses field effect transistor (FET) devices to sense the surface charge, amplify it and produce a detectable output signal. With the FET device, hybridization can be detected at lower volumes and concentrations. The FET device is based on solution processed ZnO nano layers as the semiconductor channel. Since the design uses a low cost fabrication procedure, the sensors can be disposed economically after successful completion of the measurements. Furthermore the presented ZnO FET device benefits from double gate advantages. The bottom gate is used to provide the required initial bias conduction channel while the top gate is used to modulate the threshold voltage using the surface charge variations. The effect of platinum nano particles on thiolated DNA probe assembly at the sensor surface is also investigated in this paper. The presented concept is evaluated using a probe station instrument. The input–output transfer curve of the FET is extracted for different surface configurations including DNA probe, DNA probe hybridized with a match (complementary) target and DNA probe coated with un-match DNA sequence. It is shown that the hybridization can be identified with threshold voltage shifts of the transfer curve. It is also observed that the nano platinum linkers increase the sensor’s sensitivity.