Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Mechanical Engineering

Degree Level

Undergraduate

Department

Mechanical Engineering

Advisor/Mentor

Steve Tung

Committee Member

Han Hu

Abstract

Dr. Steve Tung’s research lab is developing a device for sequencing DNA strands. A key component of this device is a nano sensor fabricated using monolayer graphene. To create the sensor, the graphene must be precisely patterned. Graphene, a single layer of carbon atoms, is an ideal material for detecting electrical signals from DNA bases due to its excellent conductivity.

The current fabrication method uses Atomic Force Microscopy (AFM) in combination with Electrode-Free Local Anodic Oxidation (LAO) lithography. While AFM is typically employed for nanoscale imaging, pairing it with LAO lithography enables the patterning of graphene into nanoribbons capable of capturing current signals from DNA bases. In the LAO process, a direct-current voltage is applied to the AFM tip, which induces an oxidation reaction by attracting water molecules [1]. Several factors influence the effectiveness of this process, including the set point, applied voltage, and tip speed.

The goal of the project was to improve the patterning resolution by reducing the cut width from 80 nanometers while ensuring the cut depth remained under 2 nanometers. The final results achieved the depth target but did not meet the desired width.

Keywords

Graphene; Nanotechnology; Local Anodic Oxidation Lithography

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