Comparing solution-gate and bottom-gate nanowire field-effect transistors on pH sensing with different salt...

Area of Science:

• * Materials Science and Nanotechnology
• * Chemical and Biosensing Technologies

Background:

• * Field-effect transistors (FETs) are adaptable for pH sensing using diverse structures and materials.
• * Extended-gate (EG), floating-gate, and dual-gate (DG) FET designs can improve sensor performance.

Purpose of the Study:

• * To evaluate solution-gate and bottom-gate FETs for pH sensing.
• * To investigate the impact of buffer ionic concentrations on sensor signals.
• * To explore the role of hafnium dioxide (HfO2) surface charge and polyethylene glycol (PEG) modification.

Main Methods:

• * Fabrication and testing of solution-gate and bottom-gate FETs.
• * Utilizing hafnium dioxide (HfO2) as the sensing film.
• * Employing buffers with varying ionic concentrations (e.g., bis-tris propane - BTP).
• * Investigating the effect of silane-PEG-OH modification.

Main Results:

• * Solution-gate FETs demonstrated high pH sensitivity near the Nernst limit (59.2 mV/pH), even in high ionic strength BTP solutions.
• * Silane-PEG-OH modification helped reduce signal deviations during pH sensing.
• * Bottom-gate FETs performed less effectively in high ionic strength buffers but were suitable for low ionic concentrations (0.1-10 mM BTP).

Conclusions:

• * Solution-gate FETs offer robust pH sensing capabilities in high ionic strength environments.
• * The study highlights the importance of surface modification and gate configuration for FET-based pH sensors.
• * Solution-gate FETs show promise for detecting biomolecules under physiological conditions.