Fundamental efficiency of nanothermophones

Modeling and experiments

Visa Vesterinen (Corresponding Author), Antti O. Niskanen, Juha Hassel, Panu Helistö

Research output: Contribution to journalArticleScientificpeer-review

74 Citations (Scopus)

Abstract

Scaling down the dimensions of thermoacoustic sound sources (thermophones) improves efficiency by means of reducing speaker heat capacity. Recent experiments with nanoscale thermophones have revealed properties which are not fully understood theoretically. We develop a Green’s function formalism which quantitatively explains some observed discrepancies, e.g., the effect of a heat-absorbing substrate in the proximity of the sound source. We also find a generic ultimate limit for thermophone efficiency. We verify the theory with experiments and finite difference method simulations which deal with thermoacoustically operated suspended arrays of nanowires. The efficiency of our devices is measured to be 1 order of magnitude below the ultimate bound. At low frequencies this mainly results from the presence of a substrate. At high frequencies, on the other hand, the efficiency is limited by the heat capacity of the nanowires. Measured sound pressure level and efficiency are in good agreement with simulations. We discuss the feasibility of reaching the ultimate limit in practice.
Original languageEnglish
Pages (from-to)5020-5024
Number of pages5
JournalNano Letters
Volume10
Issue number12
DOIs
Publication statusPublished - 2010
MoE publication typeA1 Journal article-refereed

Fingerprint

Acoustic waves
Experiments
Nanowires
Specific heat
nanowires
specific heat
Thermoacoustics
acoustics
Substrates
sound pressure
Green's function
Finite difference method
proximity
Green's functions
simulation
formalism
low frequencies
scaling
heat
Hot Temperature

Keywords

  • Thermoacoustic
  • sound generation
  • suspended metal wire
  • frequency response
  • acoustic efficiency
  • ultrasound

Cite this

Vesterinen, Visa ; Niskanen, Antti O. ; Hassel, Juha ; Helistö, Panu. / Fundamental efficiency of nanothermophones : Modeling and experiments. In: Nano Letters. 2010 ; Vol. 10, No. 12. pp. 5020-5024.
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abstract = "Scaling down the dimensions of thermoacoustic sound sources (thermophones) improves efficiency by means of reducing speaker heat capacity. Recent experiments with nanoscale thermophones have revealed properties which are not fully understood theoretically. We develop a Green’s function formalism which quantitatively explains some observed discrepancies, e.g., the effect of a heat-absorbing substrate in the proximity of the sound source. We also find a generic ultimate limit for thermophone efficiency. We verify the theory with experiments and finite difference method simulations which deal with thermoacoustically operated suspended arrays of nanowires. The efficiency of our devices is measured to be 1 order of magnitude below the ultimate bound. At low frequencies this mainly results from the presence of a substrate. At high frequencies, on the other hand, the efficiency is limited by the heat capacity of the nanowires. Measured sound pressure level and efficiency are in good agreement with simulations. We discuss the feasibility of reaching the ultimate limit in practice.",
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Fundamental efficiency of nanothermophones : Modeling and experiments. / Vesterinen, Visa (Corresponding Author); Niskanen, Antti O.; Hassel, Juha; Helistö, Panu.

In: Nano Letters, Vol. 10, No. 12, 2010, p. 5020-5024.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Fundamental efficiency of nanothermophones

T2 - Modeling and experiments

AU - Vesterinen, Visa

AU - Niskanen, Antti O.

AU - Hassel, Juha

AU - Helistö, Panu

N1 - Project code: 30356

PY - 2010

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AB - Scaling down the dimensions of thermoacoustic sound sources (thermophones) improves efficiency by means of reducing speaker heat capacity. Recent experiments with nanoscale thermophones have revealed properties which are not fully understood theoretically. We develop a Green’s function formalism which quantitatively explains some observed discrepancies, e.g., the effect of a heat-absorbing substrate in the proximity of the sound source. We also find a generic ultimate limit for thermophone efficiency. We verify the theory with experiments and finite difference method simulations which deal with thermoacoustically operated suspended arrays of nanowires. The efficiency of our devices is measured to be 1 order of magnitude below the ultimate bound. At low frequencies this mainly results from the presence of a substrate. At high frequencies, on the other hand, the efficiency is limited by the heat capacity of the nanowires. Measured sound pressure level and efficiency are in good agreement with simulations. We discuss the feasibility of reaching the ultimate limit in practice.

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KW - suspended metal wire

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KW - acoustic efficiency

KW - ultrasound

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