Modeling of graphene Hall effect sensors for microbead detection

TL;DR

This paper presents a model for graphene Hall sensors used in microbead detection, validated experimentally, and analyzes factors affecting sensitivity such as defects, bead magnetization, distance, and device size.

Contribution

It introduces a validated model for graphene Hall sensors and provides a comprehensive numerical analysis of factors influencing their sensitivity in microbead detection.

Findings

Sensor sensitivity decreases with material defects and increased bead distance.

High magnetic fields cause bead magnetization saturation, reducing signal.

Device width and defect levels significantly impact detection performance.

Abstract

This paper deals with the modeling of sensitivity of epitaxial graphene Hall bars, from sub-micrometer to micrometer size, to the stray field generated by a magnetic microbead. To demonstrate experiment feasibility, the model is first validated by comparison to measurement results, considering an ac-dc detection scheme. Then, an exhaustive numerical analysis is performed to investigate signal detriment caused by material defects, saturation of bead magnetization at high fields, increment of bead distance from sensor surface and device width increase.