Performance Enhancement of Biomolecule Detection in ZnO Thin-Film Transistor by Noise Spectroscopy Measurements

In this paper, effectiveness of noise spectroscopy measurements have been investigated for enhancing the reliability of biomolecule detection in complex analyte like serum using zinc oxide (ZnO) thin film transistor (TFT). Different gate voltages have been applied to study the noise spectrum after the capture of a specific Hep-B surface antigen (HBsAg). It has been observed that the noise spectrum exhibits a Lorentzian behavior after biomolecule capture with a distinct corner frequency at an optimum gate voltage of 0.5V. This has been attributed to significant modulation in drain current upon biomolecule capture along with a low device noise. The corner frequencies for different concentration of biomolecules are considerably less overlapping in serum compared to drain current sensitivities which has resulted in antigen detection down to 1fM within an error of ±5%. The present study lowers the detection limit by more than one order of magnitude compared to the existing reports of antigen detection in serum using ZnO nanostructures.