Fabrication and Characterization of a Thermophone Based on Laser-Scribed Graphene Intercalated with Multiwalled Carbon Nanotubes.

Moin Rabbani,Syed Khalid,Mohammad Ali Mohammad,Aashir Waheed Syed

doi:10.3390/nano11112874

Moin Rabbani, Syed Khalid + Show 2 more

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https://doi.org/10.3390/nano11112874

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Abstract

The low sound pressure level and high operating voltages of thermophones have limited their applications in the past. However, in recent years, utilizing nanomaterials in thermophones has improved their efficiency and applicability. Nanomaterials, especially carbon nanotubes and graphene, have the advantage of low heat capacity per unit area (HCPUA) and high electrical and thermal conductivity. Therefore, they require a low electrical input power and generate a high sound pressure level (SPL) by efficiently transferring heat to the surrounding fluid. Laser-scribed graphene (LSG) can generate smooth spectra acoustic emissions over a wide range of frequencies by means of thermoacoustic (TA) emission. In this work, a thermophone based on LSG intercalated with multiwalled carbon nanotubes (MWCNTs) is proposed. The effects of varying input power, duty cycle percentage and measuring distance on the sound pressure level (SPL) of thermophones are studied to extract maximum efficiency. The achieved SPL of LSG, normalized to the input power, has increased by approximately 11 dB by intercalating it with MWCNTs, which shows that our proposed material can be a potential candidate for an efficient thermophone.

Highlights

In conventional loudspeakers, sound is produced by the mechanical vibration of a diaphragm while in thermoacoustic loudspeakers, sound is produced by exchanging the produced Joule heating to the surrounding fluid and generating acoustic waves, without the need of any physically vibrating parts
Raman spectra of Laser-scribed graphene (LSG) and LSG+multiwalled carbon nanotubes (MWCNTs) are shown in Figure 3a,b, respectively
The ID /IG of LSG was found to be 1.01, which is higher than the ID /IG of LSG+MWCNTs (0.94); this is mainly due to decreased crystallinity of LSG

Summary

Introduction

Sound is produced by the mechanical vibration of a diaphragm while in thermoacoustic loudspeakers, sound is produced by exchanging the produced Joule heating to the surrounding fluid and generating acoustic waves, without the need of any physically vibrating parts. Thermophones are lightweight, flexible, transparent and low cost, which makes them a better alternative to conventional loudspeakers. Thermophones do not require any mechanical parts and rare earth metals, which makes them preferable over conventional loudspeakers. Thermophones, or thermoacoustic loudspeakers, were first invented by Arnold and Crandall in 1917 [1]. The thermophone made by Arnold and Crandall consisted of a thin platinum wire. The progress in thermophones halted for a century due to the high heat capacity of bulk materials, which caused the low yield of thermophones at high operating voltages

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