Affiliations: [a] BAM Federal Institute for Materials Research and
Testing, Berlin, Germany
Correspondence:
[*]
Corresponding author: Andrea Harrer, BAM Federal Institute for
Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany.
Tel.: +49 30 8104 4413; Fax: +49 30 8104 1845; E-mail: andrea.harrer@bam.de
Abstract: The generation of airborne ultrasound is presented using the
thermoacoustic principle applied to carbon materials at the micro- and
nanoscale. Such materials are shown to be capable of emitting ultrasound when
being fed by an alternating current. We tested the acoustic performance of
carbon fibers, bucky papers and electrospun polyacrylonitrile-derived carbon
nanofibers and determined the sound pressure for frequencies up to 350 kHz. A
comparison between the experimental results and the theoretical prediction
showed remarkable agreement for frequencies up to 150 kHz. Beyond 150 kHz, we
found slight deviations from the expected sound pressure dependence on the
square root of the frequency.
