On-chip surface modified nanostructured ZnO as functional pH sensors

Area of Science:

• Materials Science
• Nanotechnology
• Sensor Technology

Background:

• Zinc oxide (ZnO) nanostructures are explored for electronic applications in biological and chemical sensing.
• Extended-gate field-effect transistors (EGFETs) offer a platform for developing novel chemical sensors.

Purpose of the Study:

• To synthesize and characterize ZnO ultra-fine nanowire (NW) and nanoflake (NF) hybrid structures.
• To integrate these ZnO nanostructures into EGFETs for pH sensing applications.
• To investigate the influence of nanostructure morphology and surface modification on sensor performance.

Main Methods:

• Au-assisted chemical vapor deposition (CVD) for ZnO nanostructure synthesis.
• Scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM) for characterization.
• Fabrication and testing of EGFETs with ZnO nanostructure gate electrodes for pH sensing.

Main Results:

• Successfully synthesized ZnO NW and NW-NF hybrid structures.
• ZnO NWs exhibited superior pH sensing performance compared to NW-NF hybrids due to higher surface-to-volume ratio.
• (3-Aminopropyl)triethoxysilane (APTES) surface coating improved device stability and extended the dynamic pH sensing range.

Conclusions:

• Ultra-fine ZnO nanowires are effective gate electrodes for high-performance EGFET-based pH sensors.
• Surface functionalization with APTES enhances the robustness and operational range of ZnO nanostructure sensors.
• The findings contribute to the development of advanced ZnO-based electrochemical sensing devices.