Honors Theses

Date of Award

2018

Document Type

Undergraduate Thesis

Department

Electrical Engineering

First Advisor

Paul Goggans

Relational Format

Dissertation/Thesis

Abstract

The purpose of this research project is to design a multi-purpose fMRI-compatible vibrotactile skin stimulator that can be used in varying felds of research so that a specifc design does not have to be built for each individual application. Throughout this project, several stimulator designs were produced, but the core idea for each was quite similar. In each design, a wire coil was wound on a exible plastic tape former. One point of each coil is fxed, and the opposite point provides stimulation. Each wire coil was placed in a constant magnetic feld, which provided a weaker version of the magnetic feld present in an fMRI bore. Inside this feld, each coil was driven using a current source, which creates a force on each segment of the coil that is determined by the equation F= I L × B. The result of these forces on the segments of the coils is a torque in the joints of the coils. Depending on the direction of the current in the coils, this torque causes the coils to either extend upward or contract downward. When these coils were driven in the audible frequency band (85 to 255 Hz), the oscillating contraction and extension of the coils provided vibrotactile stimulation that can be detected by humans. Each stimulator design was tested for functionality through measurements of its admittance versus frequency as well as its force per current transfer function versus frequency. These tests were utilized to evaluate which of the stimulator designs properly provided vibrotactile feedback while inside a magnetic feld for the intended frequency band of use and also allowed for the determination of the most practical skin stimulator design.

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