Date of Award

2017

Document Type

Open Access Master's Report

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Andrew R. Barnard

Committee Member 1

Jason R. Blough

Committee Member 2

Charles van Karsen

Committee Member 3

Darrell Robinette

Abstract

Super-aligned carbon nanotube (CNT) thin-film is used to create thermophones. The thermal properties of CNT film allow it to rapidly heat and cool when supplied AC power producing temperature and pressure gradients and, therefore, audible sound. The advantages of CNT thermophones include eliminating all moving components of traditional speakers and reducing the weight of the speaker itself by using CNT film, which is nearly weightless. Additionally, the flexibility of CNT film provides the unique opportunity to construct loudspeakers of various sizes and geometries. In this work, a spherical CNT thermophone is designed, manufactured, and tested for directivity with the overall goal of creating a perfectly omnidirectional sound source over a wide frequency band. The spherical CNT thermophone is found to have significant directivity associated with it at the lowest and highest audible frequency bands, while performance is nearly omnidirectional at middle frequency bands. The second part of this work uses of the same CNT thin-film as a microphone through hot-film anemometry sensing the particle velocity in acoustic waves of pure frequency tones. The advantages of a CNT hot-film microphone are similar to those of CNT thermophones and include the ability to construct microphones of various sizes and shapes because the film is ultra-lightweight and flexible. The microphone’s sensitivity, power requirements, and frequency response were investigated. Results indicate that it may be feasible to use a CNT hot-film anemometer configuration as a microphone for detecting pure frequency tones across a large frequency range.

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