Simple graphene chemiresistors as pH sensors: fabrication and characterization

TL;DR

This paper presents a straightforward, gate-free graphene-based pH sensor fabricated via mechanical exfoliation and focused ion beam techniques, demonstrating linear resistance changes with pH and potential for miniaturized applications.

Contribution

The study introduces a simple, fabrication-friendly graphene pH sensor with linear response and high resolution, suitable for micro/nano-scale applications.

Findings

Resistance decreases linearly with pH in 4-10 range

Resolution of approximately 0.3 pH units achieved

Sensitivity of about 2 kΩ/pH

Abstract

We report the fabrication and characterization of a simple gate-free graphene device as a pH sensor. The graphene sheets are made by mechanical exfoliation. Platinum contact electrodes are fabricated with a mask-free process using focused ion beam, and then expanded by silver paint. Annealing is used to improve the electrical contact. The experiment on the fabricated graphene device shows that the resistance of the device decreases linearly with increasing pH values (in the range of 4-10)in the surrounding liquid environment. The resolution achieved in our experiments is approximately 0.3 pH in alkali environment. The sensitivity of the device is calculated as approximately 2 k\Omega /pH. The simple configuration, miniaturized size and the integration ability make graphene-based sensors promising candidates for future micro/nano applications.