Improving the detecting sensitivity of transistor-based DNA sensor by the optimization of channel thicknesses

Abstract

Organic thin-film transistor (OTFT) has been adopted as a promising sensing platform to detect DNA target molecules by analyzing their electrical parameters. The source/drain current ratio of OTFT (with and without DNA molecules) as the sensor sensitivity have been widely utilized to detect and identify DNA molecules. In this paper, pentacene as a typical organic semiconductor with various thin-film thicknesses have been adopted as the active layer of OTFT that induce to the changeable sensor sensitivity for the DNA molecules. Importantly, the sensitivity of the device shows the remarkable dependence in the applied gate voltages (VG) and an improved trend is observed with the lowering of VG. Importantly, a ten-fold improvement in the sensor sensitivity is achieved by the optimization of channel thicknesses at the low VG condition. Furthermore, the variable-temperature measurements are carried out to explore the charge mechanism of OTFT induced by the DNA molecules. Our studies indicate the sensor sensitivity is mainly determined by the charge-injection process of OTFT arisen in the linear region. Current work will be helpful for deeply understanding the operating mechanism of OTFT-based biosensors.