Highly Sensitive ZnO NWFET Biosensor Fabricated Using Top-Down Processes

Nonofo M.J Ditshego

doi:10.4028/www.scientific.net/jnanor.55.66

Abstract

A highly sensitive low-doped ZnO nanowire field effect transistor (NWFET) biosensor has been fabricated and measured. The low doped biosensor with NWFET transducer was used to sense charge of the following substances: lysozyme (LYSO), phosphate buffered saline (PBS), bovine serum albumin (BSA). It achieved maximum sensitivity of -543.2 % for the PBS-LYSO protein and 13,069 % for the PBS-BSA protein. These results were achieved because the electrical measurement and characterisation was focused on the charge effect of the LYSO and BSA acting on the ZnO nanowire subthreshold region. The nano-fabrication process is stable and reproducible. The high sensitivity of the ZnO NWFET biosensor can be exploited for selective analyte detection by functionalizing the nanowire surface with antibodies and/or other biomolecular probe molecules.

Highlights

Researchers [1,2,3,4,5,6,7,8,9,10] continue to investigate zinc oxide nanowire field effect transistor (NWFET) transducer as a sensing agent for protein molecules
This paper presents a highly sensitive biosensor that uses top-down passivated ZnO NWFET as a transducer
The high sensitivity is achieved because the electrical measurements and characterisation focuses on the charge effect of the lysozyme from chicken white (LYSO: Fluka 62970) and bovine serum albumin (BSA: Sigma A3059) acting on the ZnO nanowire subthreshold region which possess a logarithmic scale

Summary

Introduction

Researchers [1,2,3,4,5,6,7,8,9,10] continue to investigate zinc oxide nanowire field effect transistor (NWFET) transducer as a sensing agent for protein molecules. To further increase device sensitive, three things are investigated: gate oxide made of Al2O3, low doping and the nanowire structure [1, 20] of the ZnO channel. The high sensitivity is achieved because the electrical measurements and characterisation focuses on the charge effect of the lysozyme from chicken white (LYSO: Fluka 62970) and bovine serum albumin (BSA: Sigma A3059) acting on the ZnO nanowire subthreshold region which possess a logarithmic scale. By reducing the DEZ dose time from 1.0 s to 50 ms, it caused the O content to be much higher than the Zn content which increased the doping concentration This means oxygen interstitials Oi and oxygen antisite defects OZn have more effect on the doping concentration than oxygen vacancies Vo. To reduce the interface state charge, the ZnO deposition recipe was modified. The mechanism of the protein adsorption on the Al2O3 surface is in equilibrium with the protein concentration in solution

Step 2

Results

Discussion

Conclusion