Session: 15-01-01: ASME International Undergraduate Research and Design Exposition

Paper Number: 145353

145353 - Spinning Current Technique for Graphene-Based Hall Sensors 

Spinning Current Technique (SCT) is a definitive solution to counter the inherent offset voltage challenge in Hall plates, crucial devices for magnetic field detection. SCT involves the controlled rotation of terminals to preserve the induced Hall voltage polarity while reversing the offset voltage polarity, offering a groundbreaking resolution. Leveraging the distinctive properties of Hall plates, the study introduces a specifically designed SCT circuit for a chosen Hall plate, demonstrating remarkable accuracy in simulations. The paper proposes advancing the SCT for Graphene-based Hall sensors, capitalizing on Graphene's superior characteristics for heightened sensitivity, linearity, and temperature stability. The primary objective is the integration of SCT into Graphene Hall Sensors, potentially resulting in cost-effective, highly sensitive magnetic sensors. The adaptability of Hall plates allows for testing on various plates to evaluate performance. The paper underscores critical parameters such as Hall voltage, offset voltage, power supply ratings, and temperature considerations. While existing products target similar goals, the uniqueness of this study lies in implementing SCT on Graphene Hall plates. The intended users are manufacturers of commercial Hall sensors, applicable in diverse fields such as current measurement, magnetometry, positional sensing, motion tracking, and geomagnetic field measurement. In our circuit design, we integrate a series of CMOS analog switches, pivotal components enabling the controlled rotation of terminals essential to the functionality of the Spinning Current Technique (SCT). The incorporation of CMOS analog switches not only enhances precision but also bolsters the reliability of the switching mechanism, thus augmenting the overall efficacy of the circuit. At the amplification stage, we employ an instrumentation amplifier boasting a tunable gain of up to 300. This tunable gain feature facilitates customization tailored to the specific characteristics of the Hall plate and the magnitude of the magnetic field under measurement, thereby ensuring optimal signal amplification and accuracy in the output readings. Our SCT circuit prioritizes signal quality, striving for a Signal-to-Noise Ratio (SNR) exceeding 60 decibels in response to the smallest input field, typically in the micro Tesla range. This stringent SNR specification underscores our commitment to maintaining high sensitivity while mitigating noise, a critical aspect for the reliable detection of weak magnetic fields across diverse applications. To validate the functionality of the Hall element, we have devised a setup tailored for practical testing. Given that the Hall element yields Hall voltage in response to the average magnetic field perpendicular to its active area, the magnetic field must exhibit both constancy and uniformity across space. This ensures that the Hall element perceives a consistent field magnitude at every point within its active area, with magnetic field lines traversing in a perpendicular direction to the active area. To generate such a uniform magnetic field, we have meticulously designed and constructed a Helmholtz coil setup. This setup comprises the Helmholtz coil itself, the SCT printed circuit board (PCB), an FPGA (Field-Programmable Gate Array), and a daughter board housing the Hall element. By employing this comprehensive setup, we can effectively assess the performance and accuracy of the SCT circuit in real-world conditions, validating its capability to reliably detect and measure magnetic fields across various applications and environments.

Presenting Author: Ashutosh Shrama M S Ramaiah Institute of Technology

Presenting Author Biography: Ashutosh Sharma is currently an undergraduate student pursuing a Bachelor of Engineering in Mechanical Engineering at M S Ramaiah Institute of Technology, Bangalore, India. His current research interests include aerospace and military technology, robotics, nuclear and thermal engineering, chemistry, operations research, and applied mathematics.

Authors:

Ashutosh Shrama M S Ramaiah Institute of Technology
Vinit Shenvi M S Ramaiah Institute of Technology
Gokul P Patel M S Ramaiah Institute of Technology
Adhithi M M S Ramaiah Institute of Technology